Engineered transaminase and methods of making and using

ABSTRACT

Disclosed are transaminase (TA) enzymes and nucleic acids encoding them. In some cases, the transaminase enzymes are non-natural, engineered transaminases. Also disclosed are biosynthetic methods and engineered microorganisms that enhance or improve the biosynthesis of 6-aminocaproate, hexamethylenediamine, caproic acid, caprolactone, or caprolactam. The engineered microorganisms include exogenous TA and in some cases engineered TA.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Patent Application Ser. Nos. 62/837,888, filed Apr. 24, 2019; 62/860,123, filed Jun. 11, 2019; and 62/860,160, filed Jun. 11, 2019, the disclosures of which are incorporated by reference herein in their entirety.

INCORPORATION OF SEQUENCE LISTING

This application contains a sequence listing titled “GN000100WO Sequence Listing.txt,” which was created Apr. 24, 2020 and is 154 kilobytes in size. The sequence listing is incorporated herein by reference.

BACKGROUND

Nylons are polyamides that can be synthesized by the condensation polymerization of a diamine with a dicarboxylic acid or the condensation polymerization of lactams. Nylon 6,6 is produced by reaction of hexamethylenediamine (HMD) and adipic acid, while nylon 6 is produced by a ring opening polymerization of caprolactam. Therefore, adipic acid, hexamethylenediamine, and caprolactam are important intermediates in nylon production.

Microorganisms have been engineered to produce some of the nylon intermediates. However, engineered microorganisms can produce undesirable byproducts as a result of undesired enzymatic activity on pathway intermediates and final products. Such byproducts and impurities therefore increase, cost, and complexity of biosynthesizing compounds and can decrease efficiency or yield of the desired products.

SUMMARY

Provided herein are non-naturally occuring, engineered transaminase (TA) enzymes that react with adipate semialdehyde to form 6-aminocaproic acid (6ACA). The TA enzymes are encoded by the amino acid SEQ ID NO: 1, 13 or 31. Transaminases of SEQ ID NO:1, 13, or 31 are engineered to have better activity or specificity for adipate semialdehyde compared to the wild-type SEQ ID NO:1, 13 or 31.

Also provided herein are non-naturally occurring microbial organisms having a 6-aminocaproic acid pathway, caprolactam pathway, hexamethylenediamine pathway, caprolactone pathway, 1,6-heaxanediol pathway, or a combination of one or more of these pathways. The non-naturally occurring microbial organisms comprise at least one exogenous nucleic acid encoding a transaminase enzyme that reacts with adipate semialdehyde to form 6-aminocaproic acid (6ACA). The transaminase enzyme has a turnover number, catalytic efficiency, or a combination thereof for adipate semialdehyde substrate as for succinate semialdehyde.

The non-naturally occurring microbial organisms may further comprise additional exogenous nucleic acids encoding enzymes necessary for producing 6-aminocaproic acid, 1,6-hexanediol, caprolactone, caprolactam, hexamethylenediamine in a sufficient amount to produce the respective product. In some cases, one or more of these exogenous nucleic acids may be heterologous to the microbial organisms.

Also disclosed are methods for producing 6-aminocaproic acid, 1,6-hexanediol, caprolactone, caprolactam, hexamethylenediamine. The methods can include culturing a 6-aminocaproic acid, 1,6-hexanediol, caprolactone, caprolactam, and/or hexamethylenediamine producing non-naturally occurring microbial organisms, where the microbial organisms express at least one exogenous nucleic acid encoding a transaminase enzyme that reacts with adipate semialdehyde substrate to form 6-aminocaproic acid (6ACA).The methods include culturing the non-naturally occurring microbial organisms under conditions and for a sufficient period of time to produce 6-aminocaproic acid, 1,6-hexanediol, caprolactone, caprolactam, hexamethylenediamine.

In one embodiment is a TA comprising an amino acid sequence having at least 40% sequence identity to at least 25 or more contiguous amino acids of any of SEQ ID NO: 1, 3, 4, 5, 9, 12, 13, 26, 27, 30, 31, 38, 50, 52, 64, 74, 78, 79, 81, 91, 106, 108, and 116.

In one aspect is an engineered TA enzyme comprising one or more amino acid alterations of SEQ ID NO:1, SEQ ID NO: 13, or SEQ ID NO:31.

In one embodiment is an engineered TA enzyme comprising one or more amino acid alterations at one or more amino acid residue positions or combinations of the amino acid alterations and residue postions of SEQ ID NO:1, SEQ ID NO:13 or SEQ ID NO:31.

In some embodiments the TA enzyme comprises alterations in at least two, three, four, five, six, seven, eight, or more amino acid positions of SEQ ID NO:1, 13, or 31. In some embodiments, the amino acid alteration is an amino acid substitution. In some embodiments, the amino acid substitution is a conservative substitution. In some embodiments, the amino acid substitution is a nonconservative substitution. In some embodiments, the engineered TA comprises a transaminase activity that is at least 20% higher than the activity of the transaminase of SEQ ID NO:1, 13, or 31 with no amino acid alterations.

In one embodiment, the engineered TA has one or more amino acid alterations for one or more amino acids selected from positions corresponding to residues V114, S136, T148, P153, 1203, 1204, P206, V207, V111, T216, A237, T264, M265, and L386, G19, C22, D70, R94, D99, T109, E112, A113, F137, G144,1149, K150, Y154, S178, L186, Q208, L234, T242, A315, K318, R338, G336, L386, V390, A406, S416, A421, G17, M21, MO, A76, Y77, Q78, 179, G84, F107, T108, K119, G139, M142, A152, P153, E205, G209, G211, D238, M285, A290, G291, G292, L293, Y297, M353, S387, S388, and G392, and combinations thereof for the amino acid alteration and the residue positions of SEQ ID NO: 1. In some embodiments, the amino acid substitution is a conservative substitution. In some embodiments, the amino acid substitution is a nonconservative substitution. In some embodiments, the engineered TA comprises a transaminase activity that is at least 20% higher than the activity of the transaminase of SEQ ID NO:1 with no amino acid alterations. In some embodiments, amino acids selected from positions corresponding to residues in SEQ ID NO: 1 V114, S136, T148, P153,1203,1204, P206, V207, V111, T216, A237, T264, M265, L386, G19, C22, D70, R94, D99, T109, E112, A113, F137, G144, 1149, K150, Y154, S178, L186, Q208, L234, T242, A315, K318, R338, G336, L386, V390, A406, 5416, A421, G17, M21, A50, A76, Y77, Q78, 179, G84, F107, T108, K119, G139, M142, A152, P153, E205, G209, G211, D238, M285, A290, G291, G292, L293, Y297, M353, S387, S388, and G392 or combinations of the amino acid aleterations can be replaced. The amino acid alterations can be replaced with 19 of 20 other amino acids. In one embodiment the selected TAs and engineered TAs are capable of

-   -   a) forming 6-aminocaproic acid from an adipate semialdehyde         substrate;     -   b) forming 6-aminocaproic acid from an adipate semialdehyde         substrate at a greater rate as compared to the wild type         transaminase;     -   c) having a higher affinity for an adipate semialdehyde         substrate as compared to the wild type transaminase; or     -   d) any combination of a), b), and c).

In one embodiment is a non-naturally occurring microbial organism comprising at least one exogenous enzyme, the at least one exogenous enzyme comprising a TA converting 6-aminocaproic acid from an adipate semialdehyde substrate, the TA selected from:

-   -   (i) a transaminase comprising an amino acid sequence having at         least 50% sequence identity to at least 25 or more contiguous         amino acids of any of SEQ ID NO: 1, 3, 4, 5, 9, 12, 13, 26, 27,         30, 31, 38, 50, 52, 64, 74, 78, 79, 81, 91, 106, 108, and 116;         or     -   (ii) an engineered TA of SEQ ID NO: 1, 13, or 31.

In some embodiments, the non-naturally occurring microbial organism comprises genes encoding a 3-oxoadipyl-CoA thiolase, a 3-oxoadipyl-CoA dehydrogenase, and a 3-oxoadipyl-CoA dehydratase is able to produce at least 10% more 6ACA than a control cell that expresses the wild type TA from which the engineered TA is derived.

In some embodiments, the non-naturally occurring microbial organism comprises enzymes necessary for a 6-aminocaproic acid pathway, a hexamethylene diamine pathway, caprolactone pathway, or a caprolactam pathway. In some embodiments, the non-naturally occurring microbial organism comprises exogenous nucleic acids encoding the enzymes necessary for a caproic acid pathway, a hexamethylene diamine pathway, caprolactone pathway, or a caprolactam pathway. In some embodiments, the exogenous nucleic acids are heterologous to the microbial organism.

In one embodiment, provided are methods of producing adipyl CoA comprising culturing a non-naturally occurring microorganism of any one of the above aspects and embodiments for a sufficient time period and conditions for producing adipyl CoA.

In one embodiment, provided are methods of producing 6-aminocaproic acid (6ACA) comprising culturing a non-naturally occurring microbial organism of any one the above aspect and embodiments for a sufficient time period and conditions for producing 6ACA. In some embodiments, the methods further include recovering 6ACA from the microbial organism, fermentation broth, or both.

In one embodiment provided are methods of producing hexamethylene diamine comprising culturing a non-naturally occurring microbial organism of any one of the above aspects and embodiments for a sufficient time period and conditions for producing hexamethylene diamine. In some embodiments, the methods further include recovering hexamethylene diamine from the microbial organism, fermentation broth, or both. In some embodiments, the non-naturally occurring microbial organism comprises two, three, four, five, six, seven or more exogenous nucleic acid sequences each encoding a hexamethylene diamine pathway enzyme.

In one embodiment, provided are methods of producing 6-aminocaproic acid, 1,6-hexanediol, caprolactone, caprolactam, hexamethylenediamine comprising culturing a non-naturally occurring microbial organism of any one of the above aspects and embodiments for a sufficient time period and conditions for producing 6-aminocaproic acid, 1,6-hexanediol, caprolactone, caprolactam, hexamethylenediamine. In some embodiments, the methods further include recovering caprolactam from the microbial organism, fermentation broth, or both. In some embodiments, the non-naturally occurring microbial organism comprises two, three, four, five, six or seven exogenous nucleic acid sequences each encoding 6-aminocaproic acid, 1,6-hexanediol, caprolactone, caprolactam, hexamethylenediamine pathway enzymes.

In one embodiment, provided are bioderived 6-aminocaproic acid, hexamethylenediamine, or caprolactam synthesized using the above disclosed methods.

In some embodiments, the TA enzyme of the non-naturally occurring microbial organism has catalytic efficiency for adipate semialdehyde substrate similar to succinate semialdehyde. In some embodiments, the TA enzyme of the non-naturally occurring microbial organism further reacts with 6-aminocaproyl-CoA to form 6-aminocaproate semialdehyde.

In some embodiments, the non-naturally occurring microbial organism comprising at least one exogenous nucleic acid encoding an TA enzyme converts more adipate semialdehyde to a6-aminocaproic acid than a control microbial organism substantially identical to the non-naturally occurring microbial organism, with the exception that the control microbial organism does not comprise the exogenous nucleic acid encoding a TA enzyme.

In some embodiments, the non-naturally occurring microbial organism comprising at least one exogenous nucleic acid encoding a TA enzyme converts more more adipate semialdehyde to 6-aminocaproic acid than its wild-type microbial organism substantially identical to the non-naturally occurring microbial organism, with the exception that the wild-type microbial organism does not comprise the exogenous nucleic acid encoding an engineered TER enzyme.

In some embodiments, at least one exogenous nucleic acid encoding TA enzyme that reacts with adipate semialdehyde to form 6-aminocaproic acid is heterologous to the microbial organism.

In some embodiments, the non-naturally occurring microbial organism comprises a 6-aminocaproic acid pathway. In some embodiments, the 6-aminocaproic acid pathway comprises: (i) transaminase, (ii) 6-aminocaproate dehydrogenase, or both (iii) transaminase and 6-aminocaproate dehydrogenase enzymes. In some embodiments, the non-naturally occurring microbial organism further comprises one or more additional exogenous nucleic acids encoding one or more of the 6-aminocaproic acid pathway enzymes. In some embodiments, the exogenous nucleic acids encoding one or more of the 6-aminocaproic acid pathway enzymes are heterologous to the microbial organism.

In some embodiments, the non-naturally occurring microbial organism comprises a hexamethylenediamine pathway. In some embodiments, the hexamethylenediamine pathway comprises (i) 6-aminoacaproyl CoA transferase, (ii) 6-amino caproyl CoA synthase, (iii) 6-amino caproyl CoA reductase, (iv) hexamethylenediamine transaminase, (v) hexamethylenediamine dehydrogenase, (v) or a combination of one or more of the enzymes (i)-(v). In some embodiments, the microbial organism further comprises one or more additional exogenous nucleic acids encoding one or more of the hexamethylenediamine pathway enzymes. In some embodiments, the exogenous nucleic acids encoding one or more of the hexamethylenediamine pathway enzymes are heterologous to the microbial organism.

In some embodiments, the non-naturally occurring microbial organism comprises a caprolactam pathway. In some embodiments, the caprolactam pathway comprises aminohydrolase enzyme. In some embodiments, the microbial organism further comprises one or more additional exogenous nucleic acids encoding aminohydrolase enzyme. In some embodiments, the exogenous nucleic acids encoding aminohydrolase enzyme is heterologous to the microbial organism.

In some embodiments, the non-naturally occurring microbial organism comprises a 1, 6-hexanediol pathway. In some embodiments, the 1, 6-hexanediol pathway comprises the following enzymes: a 6-aminocaproyl-CoA transferase or synthetase catalyzing conversion of GACA to 6-aminocaproyl-CoA; a 6-aminocaproyl-CoA reductase catalyzing conversion of 6-aminocaproyl-CoA to 6-aminocaproate semialdehyde; a 6-aminocaproate semialdehyde reductase catalyzing conversion of 6-aminocaproate semialdehyde to 6-aminohexanol; a 6-aminocaproate reductase catalyzing conversion of 6ACA to 6-aminocaproate semialdehyde; an adipyl-CoA reductase adipyl-CoA to adipate semialdehyde; an adipate semialdehyde reductase catalyzing conversion of adipate semialdehyde to 6-hydroxyhexanoate; a 6-hydroxyhexanoyl-CoA transferase or synthetase catalyzing conversion of 6-hydroxyhexanoate to 6-hydroxyhexanoyl-CoA; a 6-hydroxyhexanoyl-CoA reductase catalyzing conversion of 6-hydroxyhexanoyl-CoA to 6-hydroxyhexanal; a 6-hydroxyhexanal reductase catalyzing conversion of 6-hydroxyhexanal to HDO; a 6-aminohexanol aminotransferase or oxidoreductases catalyzing conversion of 6-aminohexanol to 6-hydroxyhexanal; a 6-hydroxyhexanoate reductase catalyzing conversion of 6-hydroxyhexanoate to 6-hydroxyhexanal; an adipate reductase catalyzing conversion of ADA to adipate semialdehyde; and an adipyl-CoA transferase, hydrolase or synthase catalyzing conversion of adipyl-CoA to ADA.

In some embodiments, the non-naturally occurring microbial organism comprises pathways from adipate or adipyl-CoA to caprolactone. In some embodiments, the pathways from adipate or adipyl-CoA to caprolactone comprise the following enzymes: adipyl-CoA reductase, adipate semialdehyde reductase, 6-hydroxyhexanoyl-CoA transferase or synthetase, 6-hydroxyhexanoyl-CoA cyclase or spontaneous cyclization, adipate reductase, adipyl-CoA transferase, synthetase or hydrolase, 6-hydroxyhexanoate cyclase, 6-hydroxyhexanoate kinase, 6-hydroxyhexanoyl phosphate cyclase or spontaneous cyclization, phosphotrans-6-hydroxyhexanoylase.

In some embodiments, the TA of the non-naturally occurring microbial organism is derived from a prokaryotic species. In some embodiments, the TA enzyme is derived from Arthrobacter, Paenarthrobacter, Saccharomyces, Clostridium, Gulosibacter, Kocuria, Pseudomonas, and Alcaligenes.

In some embodiments, the non-naturally occurring microbial organism comprises a species of Acinetobacter, Actinobacillus, Anaerobiospirillum, Aspergillus, Bacillus, Clostridium, Corynebacterium, Escherichia, Gluconobacter, Klebsiella, Kluyveromyces, Lactococcus, Lactobacillus, Mannheimia, Pichia, Pseudomonas, Rhizobium, Rhizopus, Saccharomyces, Schizosaccharomyces, Streptomyces, and Zymomonas. In some embodiments, the non-naturally occurring microbial organism is a strain of Escherichia. coli.

In some embodiments, the culturing is performed in a fermentation broth comprising a sugar.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows exemplary pathways from succinyl-CoA and acetyl-CoA to 6-aminocaproate, hexamethylenediamine (HMDA), and caprolactam. The enzymes are designated as follows: A) 3-oxoadipyl-CoA thiolase, B) 3-oxoadipyl-CoA reductase, C) 3-hydroxyadipyl-CoA dehydratase, D) 5-carboxy-2-pentenoyl-CoA reductase, E) 3-oxoadipyl-CoA/acyl-CoA transferase, F) 3-oxoadipyl-CoA synthase, G) 3-oxoadipyl-CoA hydrolase, H) 3-oxoadipate reductase, I) 3-hydroxyadipate dehydratase, J) 5-carboxy-2-pentenoate reductase, K) adipyl-CoA/acyl-CoA transferase, L) adipyl-CoA synthase, M) adipyl-CoA hydrolase, N) adipyl-CoA reductase (aldehyde forming), O) 6-aminocaproate transaminase, P) 6-aminocaproate dehydrogenase, Q) 6-aminocaproyl-CoA/acyl-CoA transferase, R) 6-aminocaproyl-CoA synthase, S) amidohydrolase, T) spontaneous cyclization, U) 6-aminocaproyl-CoA reductase (aldehyde forming), V) HMDA transaminase, W) HMDA dehydrogenase, X) adipate reductase, Y) adipate kinase, Z) adipylphosphate reductase.

FIG. 2 is a graphical representation of the amino acid positions mutated in SEQ ID NO: 1.

FIG. 3 is a graphical representation of the activity of the variants relative to the wild-type SEQ ID NO: 1 control (SEQ ID NO: 1).

FIG. 4 shows an exemplary pathway for synthesis of 6-amino caproic acid and adipate using lysine as a starting point.

FIG. 5 shows an exemplary caprolactam synthesis pathway using adipyl-CoA as a starting point.

FIG. 6 shows exemplary pathways to 6-aminocaproate from pyruvate and succinic semialdehyde. Enzymes are A) HODH aldolase, B) OHED hydratase, C) OHED reductase, D) 2-OHD decarboxylase, E) adipate semialdehyde aminotransferase and/or adipate semialdehyde oxidoreductase (aminating), F) OHED decarboxylase, G) 6-OHE reductase, H) 2-OHD aminotransferase and/or 2-OHD oxidoreductase (aminating),I) 2-AHD decarboxylase, J) OHED aminotransferase and/or OHED oxidoreductase (aminating), K) 2-AHE reductase, L) HODH formate-lyase and/or HODH dehydrogenase, M) 3-hydroxyadipyl-CoA dehydratase, N) 2,3-dehydroadipyl-CoA reductase, O) adipyl-CoA dehydrogenase, P) OHED formate-lyase and/or OHED dehydrogenase, Q) 2-OHD formate-lyase and/or 2-OHD dehydrogenase. Abbreviations are: HODH=4-hydroxy-2-oxoheptane-1,7-dioate, OHED=2-oxohept-4-ene-1,7-dioate, 2-OHD=2-oxoheptane-1,7-dioate, 2-AHE=2-aminohept-4-ene-1,7-dioate, 2-AHD=2-aminoheptane-1,7-dioate, and 6-OHE =6-oxohex-4-enoate.

FIG. 7 shows exemplary pathways to hexamethylenediamine from 6-aminocapropate. Enzymes are A) 6-aminocaproate kinase, B) 6-AHOP oxidoreductase, C) 6-aminocaproic semialdehyde aminotransferase and/or 6-aminocaproic semialdehyde oxidoreductase (aminating), D) 6-aminocaproate N-acetyltransferase, E) 6-acetamidohexanoate kinase, F) 6-AAHOP oxidoreductase, G) 6-acetamidohexanal aminotransferase and/or 6-acetamidohexanal oxidoreductase (aminating), H) 6-acetamidohexanamine N-acetyltransferase and/or 6-acetamidohexanamine hydrolase (amide), I) 6-acetamidohexanoate CoA transferase and/or 6-acetamidohexanoate CoA ligase, J) 6-acetamidohexanoyl-CoA oxidoreductase, K) 6-AAHOP acyltransferase, L) 6-AHOP acyltransferase, M) 6-aminocaproate CoA transferase and/or 6-aminocaproate CoA ligase, N) 6-aminocaproyl-CoA oxidoreductase. Abbreviations are: 6-AAHOP=[(6-acetamidohexanoyl)oxy]phosphonate and 6-AHOP=[(6-aminohexanoyl)oxy]phosphonate.

FIG. 8 shows exemplary biosynthetic pathways leading to 1,6-hexanediol. A) is a 6-aminocaproyl-CoA transferase or synthetase catalyzing conversion of GACA to 6-aminocaproyl-CoA; B) is a 6-aminocaproyl-CoA reductase catalyzing conversion of 6-aminocaproyl-CoA to 6-aminocaproate semialdehyde; C) is a 6-aminocaproate semialdehyde reductase catalyzing conversion of 6-aminocaproate semialdehyde to 6-aminohexanol; D) is a 6-aminocaproate reductase catalyzing conversion of 6ACA to 6-aminocaproate semialdehyde; E) is an adipyl-CoA reductase adipyl-CoA to adipate semialdehyde; F) is an adipate semialdehyde reductase catalyzing conversion of adipate semialdehyde to 6-hydroxyhexanoate; G) is a 6-hydroxyhexanoyl-CoA transferase or synthetase catalyzing conversion of 6-hydroxyhexanoate to 6-hydroxyhexanoyl-CoA; H) is a 6-hydroxyhexanoyl-CoA reductase catalyzing conversion of 6-hydroxyhexanoyl-CoA to 6-hydroxyhexanal; I) is a 6-hydroxyhexanal reductase catalyzing conversion of 6-hydroxyhexanal to HDO; J) is a 6-aminohexanol aminotransferase or oxidoreductases catalyzing conversion of 6-aminohexanol to 6-hydroxyhexanal; K) is a 6-hydroxyhexanoate reductase catalyzing conversion of 6-hydroxyhexanoate to 6-hydroxyhexanal; L) is an adipate reductase catalyzing conversion of ADA to adipate semialdehyde; and M) is an adipyl-CoA transferase, hydrolase or synthase catalyzing conversion of adipyl-CoA to ADA.

FIG. 9 shows exemplary pathways from adipate or adipyl-CoA to caprolactone. Enzymes are A. adipyl-CoA reductase, B. adipate semialdehyde reductase, C. 6-hydroxyhexanoyl-CoA transferase or synthetase, D. 6-hydroxyhexanoyl-CoA cyclase or spontaneous cyclization, E. adipate reductase, F. adipyl-CoA transferase, synthetase or hydrolase, G. 6-hydroxyhexanoate cyclase, H. 6-hydroxyhexanoate kinase, I. 6-hydroxyhexanoyl phosphate cyclase or spontaneous cyclization, J. phosphotrans-6-hydroxyhexanoylase.

DETAILED DESCRIPTION

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which embodiments of the invention belongs. Any methods, devices and materials similar or equivalent to those described herein can be used in the practice of embodiments of the invention. The following definitions are provided to facilitate understanding of certain terms used frequently herein and are not meant to limit the scope of the present disclosure. All documents (e. g. patent applications or patents) referred to herein are incorporated by reference in their entirety.

Described are aminotransferases, also known as transaminases (E. C. 2. 6. 1) that catalyze the transfer of an amino group, a pair of electrons, and a proton from a primary amine of an amino donor substrate to the carbonyl group of an amino acceptor molecule. The desired reaction of the transaminase is to transfer the amino group of glutamate or alanine to adipate semialdehyde to form 6-aminocaproic acid (6ACA), which is shown below:

-   -   Adipate semialdehyde +Glutamate→6ACA+alpha-ketoglutaric acid

However, transaminases also have specificity for succinate semialdehyde or pyruvate as shown below:

-   -   Succinate semialdehyde+glutamate→gamma-aminobutyric         acid+alpha-ketoglutaric acid     -   Pyruvate+glutamate→alanine+alpha-ketoglutaric acid

Alanine may substitute for glutamate as the amine donor.

Described are transaminase (TA) enzymes identified to be active on an adipate semialdehyde substrate to form 6-amino caproic acid. This enzyme maybe used in various pathways leading to nylon intermediates.

The desired transaminases were identified by homology search as well as metagenomic discovery for the enzymes that can perform the desired reaction in the pathway to produce 6ACA. To evaluate the transaminase for adipate semialdehyde utilization, in some embodiments, the assay is conducted in reverse with 6ACA because adipate semialdehyde is not commercially available.

In some embodiments, a transaminase enzyme from Achromobacter xylosoxidans encoded by SEQ ID NO: 1 was identified. To identify other TA enzymes, SEQ ID NO: 1 was used. Homologous enzymes were identified as set out in Table 4. In some embodiments, transaminase enzymes or sequences are identified by BLAST. In some embodiments, the transaminase share at least about 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or 100% sequence identity, to at least 25, 50, 75, 100, 150, 200, 250, 300 or more contiguous amino acids of the amino acid sequences of the transaminase of Table 4.

In some embodiments, the transaminases identified in Table 4 share at least about 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or 100% sequence identity, to at least 25, 50, 75, 100, 150, 200, 250, 300 or more contiguous amino acids of the amino acid sequences of the transaminase of SEQ ID NO:1, 13 or 31.

In some embodiments, the transaminase enzyme have at least about 50% amino acid sequence identity to at least 25, 50, 75, 100, 150, 200, 250, 300, or more contiguous amino acids of any of SEQ ID NOs: 1, 3, 4, 5, 9, 12, 13, 26, 27, 30, 31, 38, 50, 52, 64, 74, 78, 79, 81, 91, 106, 108, and 116. In some embodiments the amino acid sequence of the transaminase enzyme that reacts with adipate semialdehyde to form 6ACA are selected from the amino acid sequences of SEQ ID NOs: 1, 3, 4, 5, 9, 12, 13, 26, 27, 30, 31, 38, 50, 52, 64, 74, 78, 79, 81, 91, 106, 108, and 116.

In some embodiments, the TA enzymes have catalytic efficiency, and/or turnover number for adipate semialdehyde as the substrate is similar to when succinate semialdehyde is the substrate. In some embodiments the enzymes with catalytic efficiency, and/or turnover number for adipate semialdehyde as the substrate that is similar to when succinate semialdehyde share at least about 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or 100% sequence identity, to at least 25, 50, 75, 100, 150, 200, 250, 300 or more contiguous amino acids of the amino acid sequences of the transaminase of SEQ ID NO: 1, 3, 4, 5, 9, 12, 13, 26, 27, 30, 31, 38, 50, 52, 64, 74, 78, 79, 81, 91, 106, 108, and 116.

A used herein, the term turnover number (also termed as k_(cat)) is defined as the maximum number of chemical conversions of substrate molecules per second that a single catalytic site will execute for a given enzyme concentration [E_(T)]. It can be calculated from the maximum reaction rate Vmax and catalyst site concentration [E_(T)] as follows:

-   -   Kcat=Vmax/[E_(T)]. The unit is s⁻¹.

As used herein the term “catalytic efficiency” is a measure of how efficiently an enzyme converts substrates into products. A comparison of catalytic efficiencies can also be used as a measure of the preference of an enzyme for different substrates (i. e., substrate specificity). The higher the catalytic efficiency, the more the enzyme “prefers” that substrate. It can be calculated from the formula: k_(cat)/K_(m), where k_(m) is the turnover number and K_(M) is the Michaelis constant, K_(M) is the substrate concentration at which the reaction rate is half of Vmax. The unit of catalytic efficiency can be expressed as s⁻¹M⁻¹.

The transaminase enzymes identified are derived from very genetically diverse organisms. Shown below are the pairwise sequence alignments of some exemplary transaminases are shown Table 1.

TABLE 1 SEQ ID SEQ ID SEQ ID NO: 1 NO: 13 NO: 31 SEQ ID NO: 1 44% 87% SEQ ID NO: 13 44% 43% SEQ ID NO: 31 87% 43%

The transaminase enzymes have conserved domains. Based on the multiple sequence alignments and hidden Markov models (HMMs), the transaminase enzymes are grouped into Pfam PF00202, of the Pfam database from the European Bioinformatics Institute (pfam.xfam.org).

In some embodiments, amino acid positions were identified for mutation in SEQ ID NO:1 by examination of the crystal structure of the protein, and the gene encoding SEQ ID NO:1 was subjected to saturation mutagenesis at selected amino acid positions. Catalytically-relevant residues were identified that can be subject to change to provide a variant amino acid with activity better than the wild-type (unmodified) SEQ ID NO: 1.

In some embodiments, transaminase enzymes are engineered to have greater specificity for the adipate semialdehyde substrate than its corresponding wild-type.

As used herein “engineered” or “variant” when used in the context of a polypeptide or nucleic acid refers to a sequence having at least one variation or alteration at an amino acid position or nucleic acid position as compared to an unmodified, wild-type sequence.

In some embodiments, the engineered transaminase has one or more alterations of an amino acid of SEQ ID NO; 1, SEQ ID NO: 13, or SEQ ID NO: 31. In some embodiments the engineered transaminase has alterations in amino acid sequences that have at least one, two, at least three, at least four, at least five, at least six, at least seven, or at least eight alterations of an amino acid with respect to SEQ ID NO:1 SEQ ID NO: 13, SEQ ID NO: 31.

In some embodiments, the engineered TA has has one or more amino acid alterations selected from one or more positions corresponding to residues V114, S136, T148, P153, 1203, 1204, P206, V207, V111, T216, A237, T264, M265 and L386, G19, C22, D70, R94, D99, T109, E112, A113, F137, G144, 1149, K150, Y154, S178, L186, Q208, L234, T242, A315, K318, R338, G336, L386, V390, A406, S416, A421, or combinations of the amino acid alterations and amino acid residue postions of SEQ ID NO:1.

In some embodiments, the one or more amino acid alteration of the engineered protein is a substitution of a conservative or non-conservative amino acid at one or more positions corresponding to residue V114, S136, T148, P153, 1203, 1204, P206, V207, V111, T216, A237, T264, M265 and L386, G19, C22, D70, R94, D99, T109, E112, A113, F137, G144, 1149, K150, Y154, S178, L186, Q208, L234, T242, A315, K318, R338, G336, L386, V390, A406, S416, and A421 or combinations of the amino acid alterations and amino acid residue postions of SEQ ID NO:1.

In some embodiments, the engineered TA has has one or more amino acid alterations of the engineered protein is an alteration at a positions corresponding to residues shown in Table 5.

In some embodiments, the engineered TA enzyme has at least catalytic efficiency for adipate semialdehyde substrate that is at least 1.5×, at least 2×, at least 5×, at least 10×, at least 25×, or 1.5-25× as compared to the corresponding wild-type of SEQ ID NOs: 1, 13, or 31.

In some embodiments; the enzymatic conversion of adipate semialdehyde by the engineered transaminase enzyme under known standard conditions is at least 10, at least 20, at least 30, at least 40, at least 50, at least 60, at least 70, at least 80, or at least 90 percent more than the enzymatic activity of the enzyme for the corresponding wild-type of SEQ ID SEQ ID NOs: 1, 13, or 31.

In some embodiments, to provide a TA variant, Achromobacter xylosoxidans TA is represented by SEQ ID NO: 1 of the disclosure is selected as a template. Variants, as described herein, can be created by introducing into the template one or more amino acid alterations (e. g. substitutions) to test for increased activity and specificity to adipate semialdehyde or analogs thereof.

For the purpose of amino acid position numbering, in some embodiments, SEQ ID NO: 1 is used as the reference sequence. Therefore, for example, mention of amino acid position 79 in reference to SEQ ID NO:1, but in the context of a different TA sequence (a target sequence or other template sequence) the corresponding amino acid position for variant creation may have the same or different position number, (e. g. 78, 79 or 80). In some cases, the original amino acid and its position on the SEQ ID NO: 1 reference template will precisely correlate with the original amino acid and position on the target TA. In other cases, the original amino acid and its position on the SEQ ID NO: 1 template will correlate with the original amino acid, but its position on the target will not be in the corresponding template position. However, the corresponding amino acid on the target can be a predetermined distance from the position on the template, such as within 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 amino acid positions from the template position. In other cases, the original amino acid on the SEQ ID NO: 1 template will not precisely correlate with the original amino acid on the target. However, one can understand what the corresponding amino acid on the target sequence is based on the general location of the amino acid on the template and the sequence of amino acids in the vicinity of the target amino acid. It is understood that sequence alignments can be generated with TA sequences not specifically disclosed herein, and such alignments can be used to understand and generate new TA variants in view of the current disclosure. In some embodiments, the sequence alignments can allow one to understand common or similar amino acids in the vicinity of the target amino acid, and those amino acids may be viewed as “sequence motif” having a certain amount of identity or similarity to between the template and target sequences. Those sequence motifs can be used to describe portions of TA sequences where variant amino acids are located, and the type of variation(s) that can be present in the motif.

In some cases, it can be useful to use the Basic Local Alignment Search Tool (BLAST) algorithm to understand the sequence identity between an amino acid motif in a template sequence and a target sequence. Therefore, in preferred modes of practice, BLAST is used to identify or understand the identity of a shorter stretch of amino acids (e. g. a sequence motif) between a template and a target protein. BLAST finds similar sequences using a heuristic method that approximates the Smith-Waterman algorithm by locating short matches between the two sequences. The (BLAST) algorithm can identify library sequences that resemble the query sequence above a certain threshold. Exemplary parameters for determining relatedness of two or more sequences using the BLAST algorithm, for example, can be as set forth below. Briefly, amino acid sequence alignments can be performed using BLASTP version 2. 0. 8 (Jan. 5, 1999) and the following parameters:Matrix: 0 BLOSUM62; gap open: 11; gap extension: 1; x_dropoff: 50; expect: 10.0; wordsize: 3; filter: on. Nucleic acid sequence alignments can be performed using BLASTN version 2. 0. 6 (Sep. 16, 1998) and the following parameters:Match: 1; mismatch: −2; gap open: 5; gap extension: 2; x_dropoff: 50; expect: 10.0; wordsize: 11; filter: off. Those skilled in the art will know what modifications can be made to the above parameters to either increase or decrease the stringency of the comparison, for example, and determine the relatedness of two or more sequences.

Site-directed mutagenesis or sequence alteration (e. g. , site-specific mutagenesis or oligonucleotide-directed) can be used to make specific changes to a target TA DNA sequence to provide a variant DNA sequence encoding TA with the desired amino acid substitution. As a general matter, an oligonucleotide having a sequence that provides a codon encoding the variant amino acid is used. In some embodiments, artificial gene synthesis of the entire coding region of the variant TA DNA sequence is performed as preferred TA targeted for substitution are generally less than 150 amino acids long.

Exemplary techniques using mutagenic oligonucleotides for generation of a variant TA sequence include the Kunkel method which may utilize a TA gene sequence placed into a phagemid. The phagemid in E. coli TA ssDNA which is the template for mutagenesis using an oligonucleotide which is a primer extended on the template.

Depending on the restriction enzyme sites flanking a location of interest in the TA DNA, cassette mutagenesis may be used to create a variant sequence of interest. For cassette mutagenesis, a DNA fragment is synthesized inserted into a plasmid, cleaved with a restriction enzyme, and then subsequently ligated to a pair of complementary oligonucleotides containing the TA variant mutation. The restriction fragments of the plasmid and oligonucleotide can be ligated to one another.

In other embodiments, another technique used to generate the variant TA sequence is PCR site directed mutagenesis. Mutagenic oligonucleotide primers are used to introduce the desired mutation and to provide a PCR fragment carrying the mutated sequence. Additional oligonucleotides may be used to extend the ends of the mutated fragment to provide restriction sites suitable for restriction enzyme digestion and insertion into the gene.

Commercial kits for site-directed mutagenesis techniques are also available. For example, the Quikchange™ kit uses complementary mutagenic primers to PCR amplify a gene region using a high-fidelity non-strand-displacing DNA polymerase such as pfu polymerase. The reaction generates a nicked, circular DNA which is relaxed. The template DNA is eliminated by enzymatic digestion with a restriction enzyme such as DpnI which is specific for methylated DNA.

In some embodiments, optimization method is directed evolution. Directed evolution is a powerful apprTAh that involves the introduction of mutations targeted to a specific gene to improve and/or alter the properties of an enzyme. Improved and/or altered enzymes can be identified through the development and implementation of sensitive high-throughput screening assays that allow the automated screening of many enzyme variants (for example, >104). Iterative rounds of mutagenesis and screening typically are performed to afford an enzyme with optimized properties. Computational algorithms that can help to identify areas of the gene for mutagenesis also have been developed and can significantly reduce the number of enzyme variants that need to be generated and screened. Numerous directed evolution technologies have been developed (for reviews, see Hibbert et al., Biomol. Eng 22:11-19 (2005); Huisman and Lalonde, In Biocatalysis in the pharmaceutical and biotechnology industries pgs. 717-742 (2007), Patel (ed.), CRC Press; Otten and Quax. Biomol. Eng 22:1-9 (2005); and Sen et al., Appl Biochem. Biotechnol 143:212-223 (2007)) to be effective at creating diverse variant libraries, and these methods have been successfully applied to the improvement of a wide range of properties across many enzyme classes. Enzyme characteristics that have been improved and/or altered by directed evolution technologies include, for example: selectivity/specificity, for conversion of non-natural substrates; temperature stability, for robust high temperature processing; pH stability, for bioprocessing under lower or higher pH conditions; substrate or product tolerance, so that high product titers can be achieved; binding (Km), including broadening substrate binding to include non-natural substrates; inhibition (Ki), to remove inhibition by products, substrates, or key intermediates; activity (kcat), to increases enzymatic reaction rates to achieve desired flux; expression levels, to increase protein yields and overall pathway flux; oxygen stability, for operation of air sensitive enzymes under aerobic conditions; and anaerobic activity, for operation of an aerobic enzyme in the absence of oxygen.

A number of exemplary methods have been developed for the mutagenesis and diversification of genes to target desired properties of specific enzymes. Such methods are well-known to those skilled in the art. Any of these can be used to alter and/or optimize the activity of a 6ACA, hexamethylenediamine or caprolactam pathway enzyme or protein. Such methods include, but are not limited to EpPCR, which introduces random point mutations by reducing the fidelity of DNA polymerase in PCR reactions (Pritchard et al., J Theor. Biol. 234:497-509 (2005)); Error-prone Rolling Circle Amplification (epRCA), which is similar to epPCR except a whole circular plasmid is used as the template and random 6-mers with exonuclease resistant thiophosphate linkages on the last 2 nucleotides are used to amplify the plasmid followed by transformation into cells in which the plasmid is re-circularized at tandem repeats (Fujii et al., Nucleic Acids Res. 32:e145 (2004); and Fujii et al., Nat. Protoc. 1:2493-2497 (2006)); DNA or Family Shuffling, which typically involves digestion of two or more variant genes with nucleases such as Dnase I or EndoV to generate a pool of random fragments that are reassembled by cycles of annealing and extension in the presence of DNA polymerase to create a library of chimeric genes (Stemmer, Proc Natl Acad Sci USA 91:10747-10751 (1994); and Stemmer, Nature 370:389-391 (1994)); Staggered Extension (StEP), which entails template priming followed by repeated cycles of 2 step PCR with denaturation and very short duration of annealing/extension (as short as 5 sec) (Zhao et al., Nat. Biotechnol. 16:258-261 (1998)); Random Priming Recombination (RPR), in which random sequence primers are used to generate many short DNA fragments complementary to different segments of the template (Shao et al., Nucleic Acids Res 26:681-683 (1998)).

Additional methods include Heteroduplex Recombination, in which linearized plasmid DNA is used to form heteroduplexes that are repaired by mismatch repair (Volkov et al, Nucleic Acids Res. 27:e18 (1999); and Volkov et al., Methods Enzymol. 328:456-463 (2000)); Random Chimeragenesis on Transient Templates (RACHETT), which employs Dnase I fragmentation and size fractionation of single stranded DNA (ssDNA) (Coco et al., Nat. Biotechnol. 19:354-359 (2001)); Recombined Extension on Truncated templates (REIT), which entails template switching of unidirectionally growing strands from primers in the presence of unidirectional ssDNA fragments used as a pool of templates (Lee et al., J. Molec. Catalysis 26:119-129 (2003)); Degenerate Oligonucleotide Gene Shuffling (DOGS), in which degenerate primers are used to control recombination between molecules; (Bergquist and Gibbs, Methods Mol. Biol 352:191-204 (2007); Bergquist et al., Biomol. Eng 22:63-72 (2005); Gibbs et al., Gene 271:13-20 (2001)); Incremental Truncation for the Creation of Hybrid Enzymes (ITCHY), which creates a combinatorial library with 1 base pair deletions of a gene or gene fragment of interest (Ostermeier et al., Proc. Natl. Acad Sci. USA 96:3562-3567 (1999); and Ostermeier et al., Nat. Biotechnol. 17:1205-1209 (1999)); Thio-Incremental Truncation for the Creation of Hybrid Enzymes (THEO-ITCHY), which is similar to ITCHY except that phosphothioate dNTPs are used to generate truncations (Lutz et al., Nucleic Acids Res 29:E16 (2001)); SCRATCHY, which combines two methods for recombining genes, ITCHY and DNA shuffling (Lutz et al., Proc. Natl. Acad Sci. USA 98:11248-11253 (2001)); Random Drift Mutagenesis (RNDM), in which mutations made via epPCR are followed by screening/selection for those retaining usable activity (Bergquist et al., Biomol. Eng. 22:63-72 (2005)); Sequence Saturation Mutagenesis (SeSaM), a random mutagenesis method that generates a pool of random length fragments using random incorporation of a phosphothioate nucleotide and cleavage, which is used as a template to extend in the presence of “universal” bases such as inosine, and replication of an inosine-containing complement gives random base incorporation and, consequently, mutagenesis (Wong et al., Biotechnol. J. 3:74-82 (2008); Wong et al., Nucleic Acids Res. 32:e26 (2004); and Wong et al., Anal. Biochem. 341:187-189 (2005)); Synthetic Shuffling, which uses overlapping oligonucleotides designed to encode “all genetic diversity in targets” and allows a very high diversity for the shuffled progeny (Ness et al., Nat. Biotechnol. 20:1251-1255 (2002)); Nucleotide Exchange and Excision Technology NexT, which exploits a combination of dUTP incorporation followed by treatment with uracil DNA glycosylase and then piperidine to perform endpoint DNA fragmentation (Muller et al., Nucleic Acids Res. 33:e17 (2005)).

Further methods include Sequence Homology-Independent Protein Recombination (SHIPREC), in which a linker is used to facilitate fusion between two distantly related or unrelated genes, and a range of chimeras is generated between the two genes, resulting in libraries of single-crossover hybrids (Sieber et al., Nat. Biotechnol. 19:456-460 (2001)); Gene Site Saturation Mutagenesis™ (GSSM™), in which the starting materials include a supercoiled double stranded DNA (dsDNA) plasmid containing an insert and two primers which are degenerate at the desired site of mutations (Kretz et al., Methods Enzymol. 388:3-11 (2004)); Combinatorial Cassette Mutagenesis (CCM), which involves the use of short oligonucleotide cassettes to replace limited regions with a large number of possible amino acid sequence alterations (Reidhaar-Olson et al. Methods Enzymol. 208:564-586 (1991); and Reidhaar-Olson et al. Science 241:53-57 (1988)); Combinatorial Multiple Cassette Mutagenesis (CMCM), which is essentially similar to CCM and uses epPCR at high mutation rate to identify hot spots and hot regions and then extension by CMCM to cover a defined region of protein sequence space (Reetz et al., Angew. Chem. Int. Ed Engl. 40:3589-3591 (2001)); the Mutator Strains technique, in which conditional is mutator plasmids, utilizing the mutD5 gene, which encodes a mutant subunit of DNA polymerase III, to allow increases of 20 to 4000-X in random and natural mutation frequency during selection and block accumulation of deleterious mutations when selection is not required (Selifonova et al., Appl. Environ. Microbiol. 67:3645-3649 (2001)); Low et al., J. Mol. Biol. 260:359-3680 (1996)).

Additional exemplary methods include Look-Through Mutagenesis (LTM), which is a multidimensional mutagenesis method that assesses and optimizes combinatorial mutations of selected amino, acids (Rajpal et al., Proc. Natl. Acad Sci. USA 102:8466-8471 (2005)); Gene Reassembly, which is a DNA shuffling method that can be applied to multiple genes at one time or to create a large library of chimeras (multiple mutations) of a single gene (Tunable GeneReassembly™ (TGR™) Technology supplied by Verenium Corporation), in Silico Protein Design Automation (PDA), which is an optimization algorithm that anchors the structurally defined protein backbone possessing a particular fold, and searches sequence space for amino acid substitutions that can stabilize the fold and overall protein energetics, and generally works most effectively on proteins with known three-dimensional structures (Hayes et al., Proc. Natl. Acad Sci. USA 99:15926-15931 (2002)); and Iterative Saturation Mutagenesis (ISM), which involves using knowledge of structure/function to choose a likely site for enzyme improvement, performing saturation mutagenesis at chosen site using a mutagenesis method such as Stratagene QuikChange (Stratagene; San Diego Calif.), screening/selecting for desired properties, and, using improved clone(s), starting over at another site and continue repeating until a desired activity is achieved (Reetz et al., Nat. Protoc. 2:891-903 (2007); and Reetz et al., Angew. Chem. Int. Ed Engl. 45:7745-7751 (2006)).

Any of the aforementioned methods for mutagenesis can be used alone or in any combination. Additionally, any one or combination of the directed evolution methods can be used in conjunction with adaptive evolution techniques, as described herein.

A cell having the desired enzymatic activity can be identified using any method known in the art. For example, enzyme activity assays can be used to identify cells having enzyme activity, see, for example, Enzyme Nomenclature, Academic Press, Inc., New York 2007. Other assays that may be used to determine reaction between of TA on adipate semialdhyde include GC/MS analysis. In other examples, levels of NADH/NADPH may be monitored. For example, the NADH/NADPH may be monitored colorimetrically or spectroscopically using NADP/NADPH assay kits (e. g. ab65349 available from ABCAM™).

The disclosed TA enzyme can be used in pathways for the production of the nylon intermediates. In some embodiments, a non-naturally occurring microorganism may be used in the production of adipate semialdehyde or other nylon intermediates that are produced using the adipate semialdehyde as an intermediate.

In some embodiments, genetically modified cells (e. g. non-naturally occurring microorganisms) are capable of producing the nylon intermediates such as 6-aminocaproic acid, caprolactam, and hexamethylenediamine.

In some embodiments, the nylon intermediates are biosynthesized using the pathway described in FIG. 1. In some embodiments, FIG. 1 pathway is provided in genetically modified cell described herein (e. g. , a non-naturally occurring microorganism) where the pathway includes at least one exogenous nucleic acid encoding a pathway enzyme expressed in a sufficient amount to produce 6-aminocaproic acid, caprolactam, and hexamethylenediamine.

In some embodiments the pathway is an HMD pathway as set forth in FIG. 1. The HMD pathway is provided in genetically modified cell described herein (e. g. , a non-naturally occurring microorganism) where the HMD pathway includes at least one exogenous nucleic acid encoding a HMD pathway enzyme expressed in a sufficient amount to produce HMD. The enzymes are 1A is a 3-oxoadipyl-CoA thiolase; 1B is a 3-oxoadipyl-CoA reductransaminasee; 1C is a 3-hydroxyadipyl-CoA dehydratransaminasee; 1D is adipate semialdehydereductransaminasee; 1E is a 3-oxoadipyl-CoA/acyl-CoA transferase; 1F is a 3-oxoadipyl-CoA synthase; 1G is a 3-oxoadipyl-CoA hydrolase; 1H is a 3-oxoadipate reductransaminasee; 1I is a 3-hydroxyadipate dehydratransaminasee; 1J is a 5-carboxy-2-pentenoate reductransaminasee; 1K is an adipyl-CoA/acyl-CoA transferase; 1L is an adipyl-CoA synthase; 1M is an adipyl-CoA hydrolase; 1N is an adipyl-CoA reductransaminasee (aldehyde forming); 1O is a 6-aminocaproate transaminase; 1P is a 6-aminocaproate dehydrogenase; 1Q is a 6-aminocaproyl-CoA/acyl-CoA transferase; 1R is a 6-aminocaproyl-CoA synthase; 1S is an amidohydrolase; 1T is spontaneous cyclization; 1U is a 6-aminocaproyl-CoA reductransaminasee (aldehyde forming); 1V is a HMDA transaminase; and 1W is a HMDA dehydrogenase.

With reference to FIG. 1, in some embodiments, the non-naturally occurring microorganism has one or more of the following pathways: ABCDNOPQRUVW; ABCDNOPQRT; or: ABCDNOPS. Other exemplary pathways that include the TA enzyme to produce adipate semialdehyde include those described in U.S. Pat. No. 8,377,680 incorporated herein by reference in its entirety.

FIG. 1 also shows a pathway from 6-aminocaproate to 6-aminocaproyl-CoA by a transferase or synthase enzyme (FIG. 1, Step Q or R) followed by the spontaneous cyclization of 6-aminocaproyl-CoA to form caprolactam (FIG. 1, Step T). In other embodiments, 6-aminocaproate is activated to 6-aminocaproyl-CoA (FIG. 1, Step Q or R), followed by a reduction (FIG. 1, Step U) and amination (FIG. 1, Step V or W) to form HMDA. 6-Aminocaproic acid can also be activated to 6-aminocaproyl-phosphate instead of 6-aminocaproyl-CoA. 6-Aminocaproyl-phosphate can spontaneously cyclize to form caprolactam. In some embodiments, 6-aminocaproyl-phosphate can be reduced to 6-aminocaproate semialdehyde, which can be then converted to HMDA as depicted in FIG. 1.

As used herein, the term “non-naturally occurring” when used in reference to a microbial organism or microorganism is intended to mean that the microbial organism has at least one genetic alteration not normally found in a naturally occurring strain of the referenced species, including wild-type strains of the referenced species. Genetic alterations include, for example, modifications introducing expressible nucleic acids encoding metabolic polypeptides, other nucleic acid additions, nucleic acid deletions and/or other functional disruption of the microbial genetic material. Such modifications include, for example, coding regions and functional fragments thereof, for heterologous, homologous or both heterologous and homologous polypeptides for the referenced species. Additional modifications include, for example, non-coding regulatory regions in which the modifications alter expression of a gene or operon. Exemplary metabolic polypeptides include enzymes within a 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid biosynthetic pathway.

A metabolic modification refers to a biochemical reaction that is altered from its naturally occurring state. Therefore, non-naturally occurring microorganisms can have genetic modifications to nucleic acids encoding metabolic polypeptides or, functional fragments thereof. Exemplary metabolic modifications are disclosed herein.

As used herein, the terms “microbial,” “microbial organism” or “microorganism” has been used interchangeably and is intended to mean any organism that exists as a microscopic cell that is included within the domains of archaea, bacteria or eukarya. Therefore, the term is intended to encompass prokaryotic or eukaryotic cells or organisms having a microscopic size and includes bacteria, archaea and eubacteria of all species as well as eukaryotic microorganisms such as yeast and fungi. The term also includes cell cultures of any species that can be cultured for the production of a biochemical.

As used herein, the term “CoA” or “coenzyme A” is intended to mean an organic cofactor or prosthetic group (nonprotein portion of an enzyme) whose presence is required for the activity of many enzymes (the apoenzyme) to form an active enzyme system. Coenzyme A functions in certain condensing enzymes, acts in acetyl or other acyl group transfer and in fatty acid synthesis and oxidation, pyruvate oxidation and in other acetylation.

As used herein, “adipate,” having the chemical formula —OOC—(CH2)4-COO— (see FIG. 1) (IUPAC name hexanedioate), is the ionized form of adipic acid (IUPAC name hexanedioic acid), and it is understood that adipate and adipic acid can be used interchangeably throughout to refer to the compound in any of its neutral or ionized forms, including any salt forms thereof. It is understood by those skilled understand that the specific form will depend on the pH.

As used herein, “6-aminocaproate,” having the chemical formula —OOC—(CH2)5-NH2 (see FIG. 1, and abbreviated as 6-ACA), is the ionized form of 6-aminocaproic acid (IUPAC name 6-aminohexanoic acid), and it is understood that 6-aminocaproate and 6-aminocaproic acid can be used interchangeably throughout to refer to the compound in any of its neutral or ionized forms, including any salt forms thereof It is understood by those skilled understand that the specific form will depend on the pH.

As used herein, “caprolactam” (IUPAC name azepan-2-one) is a lactam of 6-aminohexanoic acid (see FIG. 1, and abbreviated as CPO).

As used herein, “hexamethylenediamine,” also referred to as 1,6-diaminohexane or 1,6-hexanediamine, has the chemical formula H2N(CH2)6NH2 (see FIG. 1 and abbreviated as HMD).

As used herein, the term “substantially anaerobic” when used in reference to a culture or growth condition is intended to mean that the amount of oxygen is less than about 10% of saturation for dissolved oxygen in liquid media. The term also is intended to include sealed chambers of liquid or solid medium maintained with an atmosphere of less than about 1% oxygen.

As used herein, the term “osmoprotectant” when used in reference to a culture or growth condition is intended to mean a compound that acts as an osmolyte and helps a microbial organism as described herein survive osmotic stress. Osmoprotectants include, for example, betaines, amino acids, and the sugar trehalose. Non-limiting examples of such are glycine betaine, praline betaine, dimethylthetin, dimethylslfonioproprionate, 3-dimethylsulfonio-2-methylproprionate, pipecolic acid, dimethylsulfonioacetate, choline, L-carnitine and ectoine.

As used herein, the term “growth-coupled” when used in reference to the production of a biochemical is intended to mean that the biosynthesis of the referenced biochemical is produced during the growth phase of a microorganism. In a particular embodiment, the growth-coupled production can be obligatory, meaning that the biosynthesis of the referenced biochemical is an obligatory product produced during the growth phase of a microorganism.

As used herein, “metabolic modification” is intended to refer to a biochemical reaction that is altered from its naturally occurring state. Metabolic modifications can include, for example, elimination of a biochemical reaction activity by functional disruptions of one or more genes encoding an enzyme participating in the reaction.

As used herein, the term “gene disruption,” or grammatical equivalents thereof, is intended to mean a genetic alteration that renders the encoded gene product inactive. The genetic alteration can be, for example, deletion of the entire gene, deletion of a regulatory sequence required for transcription or translation, deletion of a portion of the gene which results in a truncated gene product, or by any of various mutation strategies that inactivate the encoded gene product. One particularly useful method of gene disruption is complete gene deletion because it reduces or eliminates the occurrence of genetic reversions in the non-naturally occurring microorganisms.

“Exogenous” as it is used herein is intended to mean that the referenced molecule or the referenced activity is introduced into the host microbial organism. The molecule can be introduced, for example, by introduction of an encoding nucleic acid into the host genetic material such as by integration into a host chromosome or as non-chromosomal genetic material such as a plasmid. Therefore, the term as it is used in reference to expression of an encoding nucleic acid refers to introduction of the encoding nucleic acid in an expressible form into the microbial organism. When used in reference to a biosynthetic activity, the term refers to an activity that is introduced into the host reference organism. The source can be, for example, a homologous or heterologous encoding nucleic acid that expresses the referenced activity following introduction into the host microbial organism. Therefore, the term “endogenous” refers to a referenced molecule or activity that is present in the host. Similarly, the term when used in reference to expression of an encoding nucleic acid refers to expression of an encoding nucleic acid contained within the microbial organism.

The term “heterologous” refers to a molecule, material, or activity derived from a source other than the referenced species whereas “homologous” refers to a molecule, material, or activity derived from the host microbial organism. Accordingly, exogenous expression of an encoding nucleic acid can utilize either or both a heterologous or homologous encoding nucleic acid.

As used herein the term “about” means ±10% of the stated value. The term “about” can mean rounded to the nearest significant digit. Thus, about 5% means 4. 5% to 5. 5%. Additionally, about in reference to a specific number also includes that exact number. For example, about 5% also includes exact 5%.

As used herein the term “bioderived” in the context of 6-aminocaproic acid, 1,6-hexanediol, caprolactone, caprolactam, or hexamethylenediamine means that these compounds are synthesized in a microbial organism.

It is understood that when more than one exogenous nucleic acid is included in a microbial organism, the exogenous nucleic acids refer to the referenced encoding nucleic acid or biosynthetic activity, as discussed above. It is further understood, as disclosed herein, that such exogenous nucleic acids can be introduced into the host microbial organism on separate nucleic acid molecules, on polycistronic nucleic acid molecules, or a combination thereof, and still be considered as more than one exogenous nucleic acid. For example, as disclosed herein a microbial organism can be engineered to express two or more exogenous nucleic acids encoding a desired pathway enzyme or protein. In the case where two exogenous nucleic acids encoding a desired activity are introduced into a host microbial organism, it is understood that the two exogenous nucleic acids can be introduced as a single nucleic acid, for example, on a single plasmid, on separate plasmids, can be integrated into the host chromosome at a single site or multiple sites, and still be considered as two exogenous nucleic acids. Similarly, it is understood that more than two exogenous nucleic acids can be introduced into a host organism in any desired combination, for example, on a single plasmid, on separate plasmids, which are not integrated into the host chromosome, and the plasmids remain as extra-chromosomal elements, and still be considered as two or more exogenous nucleic acids. The number of referenced exogenous nucleic acids or biosynthetic activities refers to the number of encoding nucleic acids or the number of biosynthetic activities, not the number of separate nucleic acids introduced into the host organism.

The non-naturally occurring microbial organisms can contain stable genetic alterations, which refers to microorganisms that can be cultured for greater than five generations without loss of the alteration. Generally, stable genetic alterations include modifications that persist greater than 10 generations, particularly stable modifications will persist more than about 25 generations, and more particularly, stable genetic modifications will be greater than 50 generations, including indefinitely.

In the case of gene disruptions, a particularly useful stable genetic alteration is a gene deletion. The use of a gene deletion to introduce a stable genetic alteration is particularly useful to reduce the likelihood of a reversion to a phenotype prior to the genetic alteration. For example, stable growth-coupled production of a biochemical can be achieved, for example, by deletion of a gene encoding an enzyme catalyzing one or more reactions within a set of metabolic modifications. The stability of growth-coupled production of a biochemical can be further enhanced through multiple deletions, significantly reducing the likelihood of multiple compensatory reversions occurring for each disrupted activity.

Those skilled in the art will understand that the genetic alterations, including metabolic modifications exemplified herein, are described with reference to a suitable host organism such as E. coli and their corresponding metabolic reactions or a suitable source organism for desired genetic material such as genes for a desired metabolic pathway. However, given the complete genome sequencing of a wide variety of organisms and the high level of skill in the area of genomics, those skilled in the art will readily be able to apply the teachings and guidance provided herein to essentially all other organisms. For example, the E. coli metabolic alterations exemplified herein can readily be applied to other species by incorporating the same or analogous encoding nucleic acid from species other than the referenced species. Such genetic alterations include, for example, genetic alterations of species homologs, in general, and in particular, orthologs, paralogs or nonorthologous gene displacements.

An ortholog is a gene or genes that are related by vertical descent and are responsible for substantially the same or identical functions in different organisms. For example, mouse epoxide hydrolase and human epoxide hydrolase can be considered orthologs for the biological function of hydrolysis of epoxides. Genes are related by vertical descent when, for example, they share sequence similarity of sufficient amount to indicate they are homologous, or related by evolution from a common ancestor. Genes can also be considered orthologs if they share three-dimensional structure but not necessarily sequence similarity, of a sufficient amount to indicate that they have evolved from a common ancestor to the extent that the primary sequence similarity is not identifiable. Genes that are orthologous can encode proteins with sequence similarity of about 25% to 100% amino acid sequence identity. Genes encoding proteins sharing an amino acid similarity less than 25% can also be considered to have arisen by vertical descent if their three-dimensional structure also shows similarities. Members of the serine protease family of enzymes, including tissue plasminogen activator and elastransaminasee, are considered to have arisen by vertical descent from a common ancestor.

Orthologs include genes or their encoded gene products that through, for example, evolution, have diverged in structure or overall activity. For example, where one species encodes a gene product exhibiting two functions and where such functions have been separated into distinct genes in a second species, the three genes and their corresponding products are considered to be orthologs. For the production of a biochemical product, those skilled in the art will understand that the orthologous gene harboring the metabolic activity to be introduced or disrupted is to be chosen for construction of the non-naturally occurring microorganism. An example of orthologs exhibiting separable activities is where distinct activities have been separated into distinct gene products between two or more species or within a single species. A specific example is the separation of elastransaminasee proteolysis and plasminogen proteolysis, two types of serine protease activity, into distinct molecules as plasminogen activator and elastransaminasee. A second example is the separation of mycoplasma 5′-3′ exonuclease and Drosophila DNA polymerase III activity. The DNA polymerase from the first species can be considered an ortholog to either or both of the exonuclease or the polymerase from the second species and vice versa.

In contrast, paralogs are homologs related by, for example, duplication followed by evolutionary divergence and have similar or common, but not identical functions. Paralogs can originate or derive from, for example, the same species or from a different species. For example, microsomal epoxide hydrolase (epoxide hydrolase I) and soluble epoxide hydrolase (epoxide hydrolase II) can be considered paralogs because they represent two distinct enzymes, co-evolved from a common ancestor, that catalyze distinct reactions and have distinct functions in the same species. Paralogs are proteins from the same species with significant sequence similarity to each other suggesting that they are homologous, or related through co-evolution from a common ancestor. Groups of paralogous protein families include HipA homologs, luciferase genes, peptidases, and others.

A nonorthologous gene displacement is a nonorthologous gene from one species that can substitute for a referenced gene function in a different species. Substitution includes, for example, being able to perform substantially the same or a similar function in the species of origin compared to the referenced function in the different species. Although generally, a nonorthologous gene displacement will be identifiable as structurally related to a known gene encoding the referenced function, less structurally related but functionally similar genes and their corresponding gene products nevertheless will still fall within the meaning of the term as it is used herein. Functional similarity requires, for example, at least some structural similarity in the active site or binding region of a nonorthologous gene product compared to a gene encoding the function sought to be substituted. Therefore, a nonorthologous gene includes, for example, a paralog or an unrelated gene.

Therefore, in identifying and constructing the non-naturally occurring microbial organisms having 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid biosynthetic capability, those skilled in the art will understand with applying the teaching and guidance provided herein to a particular species that the identification of metabolic modifications can include identification and inclusion or inactivation of orthologs. To the extent that paralogs and/or nonorthologous gene displacements are present in the referenced microorganism that encode an enzyme catalyzing a similar or substantially similar metabolic reaction, those skilled in the art also can utilize these evolutionally related genes. In gene disruption strategies, evolutionally related genes can also be disrupted or deleted in a host microbial organism, paralogs or orthologs, to reduce or eliminate activities to ensure that any functional redundancy in enzymatic activities targeted for disruption do not short circuit the designed metabolic modifications.

Orthologs, paralogs and nonorthologous gene displacements can be determined by methods well known to those skilled in the art. For example, inspection of nucleic acid or amino acid sequences for two polypeptides will reveal sequence identity and similarities between the compared sequences. Based on such similarities, one skilled in the art can determine if the similarity is sufficiently high to indicate the proteins are related through evolution from a common ancestor. Algorithms well known to those skilled in the art, such as Align, BLAST, Clustal W and others compare and determine a raw sequence similarity or identity, and also determine the presence or significance of gaps in the sequence which can be assigned a weight or score. Such algorithms also are known in the art and are similarly applicable for determining nucleotide sequence similarity or identity. Parameters for sufficient similarity to determine relatedness are computed based on well-known methods for calculating statistical similarity, or the chance of finding a similar match in a random polypeptide, and the significance of the match determined. A computer comparison of two or more sequences can, if desired, also be optimized visually by those skilled in the art. Related gene products or proteins can be expected to have a high similarity, for example, 25% to 100% sequence identity. Proteins that are unrelated can have an identity which is essentially the same as would be expected to occur by chance, if a database of sufficient size is scanned (about 5%). Sequences between 5% and 24% may or may not represent sufficient homology to conclude that the compared sequences are related. Additional statistical analysis to determine the significance of such matches given the size of the data set can be carried out to determine the relevance of these sequences.

Exemplary paramemeters for determining relatedness of two or more sequences using the BLAST algorithm, for example, can be as set forth below. Briefly, amino acid sequence alignments can be performed using BLASTP version 2. 2. 29+(Jan. 14, 2014) and the following parameTransaminase: Matrix: 0 BLOSUM62; gap open: 11; gap extension: 1; x_dropoff: 50; expect: 10.0; wordsize: 3; filter: on. Nucleic acid sequence alignments can be performed using BLASTN version 2. 0. 6 (Sep. 16, 1998) and the following parameTransaminase: Match: 1; mismatch: −2; gap open: 5; gap extension: 2; x_dropoff: 50; expect: 10.0; wordsize: 11; filter: off. Those skilled in the art will know what modifications can be made to the above parameTransaminase to either increase or decrease the stringency of the comparison, for example, and determine the relatedness of two or more sequences.

It is understood that any of the pathways disclosed herein, including those as described in the Figures can be used to generate a non-naturally occurring microbial organism that produces any pathway intermediate or product, as desired. As disclosed herein, such a microbial organism that produces an intermediate can be used in combination with another microbial organism expressing downstream pathway enzymes to produce a desired product. However, it is understood that a non-naturally occurring microbial organism that produces a 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid pathway intermediate can be utilized to produce the intermediate as a desired product.

Described herein with general reference to the metabolic reaction, reactant or product thereof, or with specific reference to one or more nucleic acids or genes encoding an enzyme associated with or catalyzing the referenced metabolic reaction, reactant or product. Unless otherwise expressly stated herein, those skilled in the art will understand that reference to a reaction also constitutes reference to the reactants and products of the reaction. Similarly, unless otherwise expressly stated herein, reference to a reactant or product also references the reaction, and reference to any of these metabolic constituents also references the gene or genes encoding the enzymes that catalyze the referenced reaction, reactant or product. Likewise, given the well-known fields of metabolic biochemistry, enzymology and genomics, reference herein to a gene or encoding nucleic acid also constitutes a reference to the corresponding encoded enzyme and the reaction it catalyzes as well as the reactants and products of the reaction.

The non-naturally occurring microbial organisms can be produced by introducing expressible nucleic acids encoding one or more of the enzymes participating in one or more 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid biosynthetic pathways. Depending on the host microbial organism chosen for biosynthesis, nucleic acids for some or all of a particular 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid biosynthetic pathway can be expressed. For example, if a chosen host is deficient in one or more enzymes for a desired biosynthetic pathway, then expressible nucleic acids for the deficient enzyme(s) are introduced into the host for subsequent exogenous expression. Alternatively, if the chosen host exhibits endogenous expression of some pathway genes, but is deficient in others, then an encoding nucleic acid is needed for the deficient enzyme(s) to achieve 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid biosynthesis. Thus, a non-naturally occurring microbial organism can be produced by introducing exogenous enzyme activities to obtain a desired biosynthetic pathway or a desired biosynthetic pathway can be obtained by introducing one or more exogenous enzyme activities that, together with one or more endogenous enzymes, produce a desired product such as 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid.

Depending on the 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid biosynthetic pathway constituents of a selected host microbial organism, the non-naturally occurring microbial organisms will include at least one exogenously expressed 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid pathway-encoding nucleic acid and up to all encoding nucleic acids for one or more adipate, 6-aminocaproic acid or caprolactam biosynthetic pathways. For example, 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid biosynthesis can be established in a host deficient in a pathway enzyme through exogenous expression of the corresponding encoding nucleic acid. In a host deficient in all enzymes of a 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid pathway, exogenous expression of all enzymes in the pathway can be included, although it is understood that all enzymes of a pathway can be expressed even if the host contains at least one of the pathway enzymes.

Given the teachings and guidance provided herein, those skilled in the art will understand that the number of encoding nucleic acids to introduce in an expressible form will, at least, parallel the adipate, 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid pathway deficiencies of the selected host microbial organism. Therefore, a non-naturally occurring microbial organism can have at least one, two, three, four, five, six, seven, eight, nine, ten, eleven or twelve, up to all nucleic acids encoding the above enzymes constituting a 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid biosynthetic pathway. In some embodiments, the non-naturally occurring microbial organisms also can include other genetic modifications that facilitate or optimize 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid biosynthesis or that confer other useful functions onto the host microbial organism. One such other functionality can include, for example, augmentation of the synthesis of one or more of the 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid pathway precursors such as succinyl-CoA and/or acetyl-CoA in the case of adipate synthesis, or adipyl-CoA or adipate in the case of 6-aminocaproic acid or caprolactam synthesis, including the adipate pathway enzymes disclosed herein, or pyruvate and succinic semialdehyde, glutamate, glutaryl-CoA, homolysine or 2-amino-7-oxosubarate in the case of 6-aminocaprioate synthesis, or 6-aminocaproate, glutamate, glutaryl-CoA, pyruvate and 4-aminobutanal, or 2-amino-7-oxosubarate in the case of hexamethylenediamine synthesis.

In some embodiments, a non-naturally occurring microbial organism has at least one exogenous nucleic acid encoding a transaminase that reacts with adipate semialdhyde to form 6ACA and selected from transaminases comprising the amino acid sequences having at least about 50% amino acid sequence identity to at least25, 50, 75, 100, 150, 200, 250, 300, or more contiguous amino acids of any of any of SEQ ID NOs: 1, 3, 4, 5, 9, 12, 13, 26, 27, 30, 31, 38, 50, 52, 64, 74, 78, 79, 81, 91, 106, 108, and 116.

Generally, a host microbial organism is selected such that it produces the precursor of a 6-aminocaproic acid, caprolactam, or hexamethylenediamine pathway, either as a naturally produced molecule or as an engineered product that either provides de novo production of a desired precursor or increased production of a precursor naturally produced by the host microbial organism. A host organism can be engineered to increase production of a precursor, as disclosed herein. In addition, a microbial organism that has been engineered to produce a desired precursor can be used as a host organism and further engineered to express enzymes or proteins of a 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid pathway.

In some embodiments, a non-naturally occurring microbial organism is generated from a host that contains the enzymatic capability to synthesize 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid. In this specific embodiment it can be useful to increase the synthesis or accumulation of a 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid pathway product to, for example, drive 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid pathway reactions toward 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid production. Increased synthesis or accumulation can be accomplished by, for example, overexpression of nucleic acids encoding one or more of the above-described 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid pathway enzymes. Over expression of the 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid pathway enzyme or enzymes can occur, for example, through exogenous expression of the endogenous gene or genes, or through exogenous expression of the heterologous gene or genes. Therefore, naturally occurring organisms can be readily generated to be non-naturally occurring microbial organisms, for example, producing 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid, through overexpression of at least one, two, three, four, five, six, seven, eight, nine, ten, eleven, twelve, thirteen, fourteen, that is, up to all nucleic acids encoding 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid biosynthetic pathway enzymes. In addition, a non-naturally occurring organism can be generated by mutagenesis of an endogenous gene that results in an increase in activity of an enzyme in the 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid biosynthetic pathway.

In particularly useful embodiments, exogenous expression of the encoding nucleic acids is employed. Exogenous expression confers the ability to custom tailor the expression and/or regulatory elements to the host and application to achieve a desired expression level that is controlled by the user. However, endogenous expression also can be utilized in other embodiments such as by removing a negative regulatory effector or induction of the gene's promoter when linked to an inducible promoter or other regulatory element. Thus, an endogenous gene having a naturally occurring inducible promoter can be up-regulated by providing the appropriate inducing agent, or the regulatory region of an endogenous gene can be engineered to incorporate an inducible regulatory element, thereby allowing the regulation of increased expression of an endogenous gene at a desired time. Similarly, an inducible promoter can be included as a regulatory element for an exogenous gene introduced into a non-naturally occurring microbial organism.

In some embodiments, a non-naturally occurring microbial organism includes one or more gene disruptions, where the organism produces a 6-ACA, adipate and/or HMDA. The disruptions occur in genes encoding an enzyme that couples production of adipate, 6-ACA and/or HMDA to growth of the organism when the gene disruption reduces the activity of the enzyme, such that the gene disruptions confer increased production of adipate, 6-ACA and/or HMDA onto the non-naturally occurring organism. Thus, in some embodiments is provided a non-naturally occurring microbial organism, comprising one or more gene disruptions, the one or more gene disruptions occurring in genes encoding proteins or enzymes wherein the one or more gene disruptions confer increased production of adipate, 6-ACA and/or HMDA in the organism. As disclosed herein, such an organism contains a pathway for production of adipate, 6-ACA and/or HMDA.

It is understood that, in methods, any of the one or more exogenous nucleic acids can be introduced into a microbial organism to produce a non-naturally occurring microbial organism. The nucleic acids can be introduced so as to confer, for example, a 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid biosynthetic pathway onto the microbial organism. Alternatively, encoding nucleic acids can be introduced to produce an intermediate microbial organism having the biosynthetic capability to catalyze some of the required reactions to confer 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid biosynthetic capability. For example, a non-naturally occurring microbial organism having a 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid biosynthetic pathway can comprise at least two exogenous nucleic acids encoding desired enzymes. In the case of adipate production, at least two exogenous nucleic acids can encode the enzymes such as the combination of succinyl-CoA: acetyl-CoA acyl transferase and 3-hydroxyacyl-CoA dehydrogenase, or succinyl-CoA: acetyl-CoA acyl transferase and 3-hydroxyadipyl-CoA dehydratransaminasee, or 3-hydroxyadipyl-CoA and adipate semialdehyde transaminase, or 3-hydroxyacyl-CoA and adipyl-CoA synthetase, and the like. In the case of caprolactam production, at least two exogenous nucleic acids can encode the enzymes such as the combination of CoA-dependent trans-enoyl-CoA reductase and transaminase, or CoA-dependent trans-enoyl-CoA reductransaminasee and amidohydrolase, or transaminase and amidohydrolase. In the case of 6-aminocaproic acid production, at least two exogenous nucleic acids can encode the enzymes such as the combination of an 4-hydroxy-2-oxoheptane-1,7-dioate (HODH) TAolase and a 2-oxohept-4-ene-1,7-dioate (OHED) hydratransaminasee, or a 2-oxohept-4-ene-1,7-dioate (OHED) hydratransaminasee and a 2-aminoheptane-1,7-dioate (2-AHD) decarboxylase, a 3-hydroxyadipyl-CoA dehydratransaminasee and a adipyl-CoA dehydrogenase, a glutamyl-CoA transferase and a 6-aminopimeloyl-CoA hydrolase, or a glutaryl-CoA beta-ketothiolase and a 3-aminopimelate 2,3-aminomutransaminasee. In the case of hexamethylenediamine production, at least two exogenous nucleic acids can encode the enzymes such as the combination of 6-aminocaproate kinase and [(6-aminohexanoyl)oxy]phosphonate (6-AHOP) oxidoreductransaminasee, or a 6-acetamidohexanoate kinase and an [(6-acetamidohexanoyl)oxy]phosphonate (6-AAHOP) oxidoreductransaminasee, 6-aminocaproate N-acetyltransferase and 6-acetamidohexanoyl-CoA oxidoreductransaminasee, a 3-hydroxy-6-aminopimeloyl-CoA dehydratransaminasee and a 2-amino-7-oxoheptanoate aminotransferase, or a 3-oxopimeloyl-CoA ligase and a homolysine decarboxylase. Thus, it is understood that any combination of two or more enzymes of a biosynthetic pathway can be included in a non-naturally occurring microbial organism.

Similarly, it is understood that any combination of three or more enzymes of a biosynthetic pathway can be included in a non-naturally occurring microbial organism , for example, in the case of adipate production, the combination of enzymes succinyl-CoA: acetyl-CoA acyl transferase, 3-hydroxyacyl-CoA dehydrogenase, and 3-hydroxyadipyl-CoA dehydratransaminasee; or succinyl-CoA: acetyl-CoA acyl transferase, 3-hydroxyacyl-CoA dehydrogenase andadipate semialdehydereductransaminasee; or succinyl-CoA: acetyl-CoA acyl transferase, 3-hydroxyacyl-CoA dehydrogenase and adipyl-CoA synthetransaminasee; or 3-hydroxyacyl-CoA dehydrogenase, 3-hydroxyadipyl-CoA dehydratransaminasee and adipyl-CoA: acetyl-CoA transferase, and so forth, as desired, so long as the combination of enzymes of the desired biosynthetic pathway results in production of the corresponding desired product. In the case of 6-aminocaproic acid production, the at least three exogenous nucleic acids can encode the enzymes such as the combination of an 4-hydroxy-2-oxoheptane-1,7-dioate (HODH) TAolase, a 2-oxohept-4-ene-1,7-dioate (OHED) hydratransaminasee and a 2-oxoheptane-1,7-dioate (2-OHD) decarboxylase, or a 2-oxohept-4-ene-1,7-dioate (OHED) hydratransaminasee, a 2-aminohept-4-ene-1,7-dioate (2-AHE) reductransaminasee and a 2-aminoheptane-1,7-dioate (2-AHD) decarboxylase, or a 3-hydroxyadipyl-CoA dehydratransaminasee, 2,3-dehydroadipyl-CoA reductransaminasee and a adipyl-CoA dehydrogenase, or a 6-amino-7-carboxyhept-2-enoyl-CoA reductransaminasee, a 6-aminopimeloyl-CoA hydrolase and a 2-aminopimelate decarboxylase, or a glutaryl-CoA beta-ketothiolase, a 3-aminating oxidoreductransaminasee and a 2-aminopimelate decarboxylase, or a 3-oxoadipyl-CoA thiolase, a 5-carboxy-2-pentenoate reductransaminasee and a adipate reductransaminasee. In the case of hexamethylenediamine production, at least three exogenous nucleic acids can encode the enzymes such as the combination of 6-aminocaproate kinase, [(6-aminohexanoyl)oxy]phosphonate (6-AHOP) oxidoreductransaminasee and 6-aminocaproic semialdehyde aminotransferase, or a 6-aminocaproate N-acetyltransferase, a 6-acetamidohexanoate kinase and an [(6-acetamidohexanoyl)oxy]phosphonate (6-AAHOP) oxidoreductransaminasee, or 6-aminocaproate N-acetyltransferase, a [(6-acetamidohexanoyl)oxy]phosphonate (6-AAHOP) acyltransferase and 6-acetamidohexanoyl-CoA oxidoreductransaminasee, or a 3-oxo-6-aminopimeloyl-CoA oxidoreductransaminasee, a 3-hydroxy-6-aminopimeloyl-CoA dehydratransaminasee and a homolysine decarboxylase, or a 2-oxo-4-hydroxy-7-aminoheptanoate TAolase, a 2-oxo-7-aminohept-3-enoate reductransaminasee and a homolysine decarboxylase, or a 6-acetamidohexanoate reductransaminasee, a 6-acetamidohexanal aminotransferase and a 6-acetamidohexanamine N-acetyltransferase. Similarly, any combination of four or more enzymes of a biosynthetic pathway as disclosed herein can be included in a non-naturally occurring microbial organism, as desired, so long as the combination of enzymes of the desired biosynthetic pathway results in production of the corresponding desired product.

In addition to the biosynthesis of 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid as described herein, the non-naturally occurring microbial organisms and methods also can be utilized in various combinations with each other and with other microbial organisms and methods well known in the art to achieve product biosynthesis by other routes. For example, one alternative to produce 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid other than use of the 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid producers is through addition of another microbial organism capable of converting an adipate, 6-aminocaproic acid or caprolactam pathway intermediate to 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid. One such procedure includes, for example, the fermentation of a microbial organism that produces a 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid pathway intermediate. The 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid pathway intermediate can then be used as a substrate for a second microbial organism that converts the 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid pathway intermediate to 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid. The 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid pathway intermediate can be added directly to another culture of the second organism or the original culture of 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid pathway intermediate producers can be depleted of these microbial organisms by, for example, cell separation, and then subsequent addition of the second organism to the fermentation broth can be utilized to produce the final product without intermediate purification steps.

In other embodiments, the non-naturally occurring microbial organisms and methods can be assembled in a wide variety of sub pathways to achieve biosynthesis of, for example, 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid. In these embodiments, biosynthetic pathways for a desired product can be segregated into different microbial organisms, and the different microbial organisms can be co-cultured to produce the final product. In such a biosynthetic scheme, the product of one microbial organism is the substrate for a second microbial organism until the final product is synthesized. For example, the biosynthesis of 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid can be accomplished by constructing a microbial organism that contains biosynthetic pathways for conversion of one pathway intermediate to another pathway intermediate or the product. Alternatively, 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid also can be biosynthetically produced from microbial organisms through co-culture or co-fermentation using two organisms in the same vessel, where the first microbial organism produces a 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid intermediate and the second microbial organism converts the intermediate to 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid.

Given the teachings and guidance provided herein, those skilled in the art will understand that a wide variety of combinations and permutations exist for the non-naturally occurring microbial organisms and methods together with other microbial organisms, with the co-culture of other non-naturally occurring microbial organisms having sub pathways and with combinations of other chemical and/or biochemical procedures well known in the art to produce 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid.

Similarly, it is understood by those skilled in the art that a host organism can be selected based on desired characteristics for introduction of one or more gene disruptions to increase production of 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid. Thus, it is understood that, if a genetic modification is to be introduced into a host organism to disrupt a gene, any homologs, orthologs or paralogs that catalyze similar, yet non-identical metabolic reactions can similarly be disrupted to ensure that a desired metabolic reaction is sufficiently disrupted. Because certain differences exist among metabolic networks between different organisms, those skilled in the art will understand that the actual genes disrupted in a given organism may differ between organisms However, given the teachings and guidance provided herein, those skilled in the art also will understand that the methods can be applied to any suitable host microorganism to identify the cognate metabolic alterations needed to construct an organism in a species of interest that will increase 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid biosynthesis. In a particular embodiment, the increased production couples biosynthesis of 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid to growth of the organism, and can obligatorily couple production of 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid to growth of the organism if desired and as disclosed herein.

Sources of encoding nucleic acids for a 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid pathway enzyme can include, for example, any species where the encoded gene product is capable of catalyzing the referenced reaction. Such species include both prokaryotic and eukaryotic organisms including, but not limited to, bacteria, including archaea and eubacteria, and eukaryotes, including yeast, plant, insect, animal, and mammal, including human. In some embodiments, the source of the encoding nucleic acids for a 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid pathway enzyme is shown in Table 4. In some embodiments, the source of the encoding nucleic acids for transaminase enzyme is shown in Table 4. In some embodiments, the source of the encoding nucleic acids for transaminase enzyme is from the genus Achromobacter, Acidaminococcus, Collinsella, Peptostreptococcaceae, Paenarthrobacter or Romboustsia. In some embodiments, the source of the encoding nucleic acids for a 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid pathway enzyme are species such as, Escherichia coli, Escherichia coli str. K12, Escherichia coli C, Escherichia coli W, Pseudomonas sp, Pseudomonas knackmussii, Pseudomonas sp. Strain B13, Pseudomonas putida, Pseudomonas fluorescens, Pseudomonas stutzeri, Pseudomonas mendocina, Rhodopseudomonas palustris, Mycobacterium tuberculosis, Vibrio cholera, Heliobacter pylori, Klebsiella pneumoniae, Serratia proteamaculans, Streptomyces sp. 2065, Pseudomonas aeruginosa, Pseudomonas aeruginosa PAO1, Ralstonia eutropha, Ralstonia eutropha H16, Clostridium acetobutylicum, Euglena gracilis, Treponema denticola, Clostridium kluyveri, Homo sapiens, Rattus norvegicus, Acinetobacter sp. ADP1, Acinetobacter sp. Strain M-1, Streptomyces coelicolor, Eubacterium barkeri, Peptostreptococcus asaccharolyticus, Clostridium botulinum, Clostridium botulinum A3 str, Clostridium tyrobutyricum, Clostridium pasteurianum, Clostridium thermoaceticum (Moorella thermoaceticum), Moorella thermoacetica Acinetobacter calcoaceticus, Mus musculus, Sus scrofa, Flavobacterium sp, Arthrobacter aurescens, Penicillium chrysogenum, Aspergillus niger, Aspergillus nidulans, Bacillus subtilis, Saccharomyces cerevisiae, Zymomonas mobilis, Mannheimia succiniciproducens, Clostridium ljungdahlii, Clostridium carboxydivorans, Geobacillus stearothermophilus, Agrobacterium tumefaciens, Achromobacter xylosoxidans, Achromobacter denitrificans, Arabidopsis thaliana, Haemophilus influenzae, Acidaminococcus fermentans, Clostridium sp. M62/1, Fusobacterium nucleatum, Bos taurus, Zoogloea ramigera, Rhodobacter sphaeroides, Clostridium beijerinckii, Metallosphaera sedula, Thermoanaerobacter species, Thermoanaerobacter brockii, Acinetobacter baylyi, Porphyromonas gingivalis, Leuconostoc mesenteroides, Sulfolobus tokodaii, Sulfolobus tokodaii 7, Sulfolobus solfataricus, Sulfolobus solfataricus, Sulfolobus acidocaldarius, Salmonella typhimurium, Salmonella enterica, Thermotoga maritima, Halobacterium salinarum, Bacillus cereus, Clostridium difficile, Alkaliphilus metalliredigenes, Thermoanaerobacter tengcongensis, Saccharomyces kluyveri, Helicobacter pylori, Corynebacterium glutamicum, Clostridium saccharoperbutylacetonicum, Pseudomonas chlororaphis, Streptomyces clavuligerus, Campylobacter jejuni, Therms thermophilus, Pelotomaculum thermopropionicum, Bacteroides capillosus, Anaerotruncus colihominis, Natranaerobius thermophilius, Archaeoglobus fulgidus, Archaeoglobus fulgidus DSM 4304, Haloarcula marismortui, Pyrobaculum aerophilum, Pyrobaculum aerophilum str. IM2, Nicotiana tabacum, Menthe piperita, Pinus taeda, Hordeum vulgare, Zea mays, Rhodococcus opacus, Cupriavidus necator, Bradyrhizobium japonicum, Bradyrhizobium japonicum USDA110, Ascarius suum, butyrate-producing bacterium L2-50, Bacillus megaterium, Methanococcus maripaludis, Methanosarcina mazei, Methanosarcina mazei, Methanocarcina barkeri, Methanocaldococcus jannaschii, Caenorhabditis elegans, Leishmania major, Methylomicrobium alcaliphilum 20Z, Chromohalobacter salexigens, Archaeglubus fulgidus, Chlamydomonas reinhardtii, trichomonas vaginalis G3, Trypanosoma brucei, Mycoplana ramose, Micrococcus luteas, Acetobacter pasteurians, Kluyveromyces lactis, Mesorhizobium loti, Lactococcus lactis, Lysinibacillus sphaericus, Candida boidinii, Candida albicans SC5314, Burkholderia ambifaria AMMD, Ascaris suun, Acinetobacter baumanii, Acinetobacter calcoaceticus, Burkholderia phymatum, Candida albicans, Clostridium subterminale, Cupriavidus taiwanensis, Flavobacterium lutescens, Lachancea kluyveri, Lactobacillus sp. 30a, Leptospira interrogans, Moorella thermoacetica, Myxococcus xanthus, Nicotiana glutinosa, Nocardia iowensis (sp. NRRL 5646), Pseudomonas reinekei MT1, Ralstonia eutropha JMP134, Ralstonia metallidurans, Rhodococcus jostii, Schizosaccharomyces pombe, Selenomonas ruminantium, Streptomyces clavuligenus, Syntrophus aciditrophicus, Vibrio parahaemolyticus, Vibrio vulnificus, as well as other exemplary species disclosed herein or available as source organisms for corresponding genes (see Examples). However, with the complete genome sequence available for now more than 550 species (with more than half of these available on public databases such as the NCBI), including 395 microorganism genomes and a variety of yeast, fungi, plant, and mammalian genomes, the identification of genes encoding the requisite 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid biosynthetic activity for one or more genes in related or distant species, including for example, homologues, orthologs, paralogs and nonorthologous gene displacements of known genes, and the interchange of genetic alterations between organisms is routine and well known in the art. Accordingly, the metabolic alterations enabling biosynthesis of 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid described herein with reference to a particular organism such as E. coli can be readily applied to other microorganisms, including prokaryotic and eukaryotic organisms alike. Given the teachings and guidance provided herein, those skilled in the art will know that a metabolic alteration exemplified in one organism can be applied equally to other organisms.

In some instances, such as when a 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid biosynthetic pathway exists in an unrelated species, 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid biosynthesis can be conferred onto the host species by, for example, exogenous expression of a paralog or paralogs from the unrelated species that catalyzes a similar, yet non-identical metabolic reaction to replace the referenced reaction. Because certain differences among metabolic networks exist between different organisms, those skilled in the art will understand that the actual gene usage between different organisms may differ. However, given the teachings and guidance provided herein, those skilled in the art also will understand that the teachings and methods can be applied to all microbial organisms using the cognate metabolic alterations to those exemplified herein to construct a microbial organism in a species of interest that will synthesize 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid.

Host microbial organisms can be selected from, and the non-naturally occurring microbial organisms generated in, for example, bacteria, yeast, fungus or any of a variety of other microorganisms applicable to fermentation processes. Exemplary bacteria include species selected from Escherichia coli, Klebsiella oxytoca, Anaerobiospirillum succiniciproducens, Actinobacillus succinogenes, Mannheimia succiniciproducens, Rhizobium etli, Bacillus subtilis, Corynebacterium glutamicum, Gluconobacter oxydans, Zymomonas mobilis, Lactococcus lactis, Lactobacillus plantarum, Streptomyces coelicolor, Clostridium acetobutylicum, Pseudomonas fluorescens, and Pseudomonas putida. Exemplary yeasts or fungi include species selected from Saccharomyces cerevisiae, Schizosaccharomyces pombe, Kluyveromyces lactis, Kluyveromyces marxianus, Aspergillus terreus, Aspergillus niger, Pichia pastoris, Rhizopus arrhizus, Rhizobus oryzae, and the like. For example, E. coli is a particularly useful host organism since it is a well characterized microbial organism suitable for genetic engineering. Other particularly useful host organisms include yeast such as Saccharomyces cerevisiae. It is understood that any suitable microbial host organism can be used to introduce metabolic and/or genetic modifications to produce a desired product.

Methods for constructing and testing the expression levels of a non-naturally occurring 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid -producing host can be performed, for example, by recombinant and detection methods well known in the art. Such methods can be found described in, for example, Sambrook et al., Molecular Cloning: A Laboratory Manual, Third Ed. , Cold Spring Harbor Laboratory, New York (2001); and Ausubel et al., Current Protocols in Molecular Biology, John Wiley and Sons, Baltimore, Md. (1999).

Exogenous nucleic acid sequences involved in a pathway for production of 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid can be introduced stably or transiently into a host cell using techniques well known in the art including, but not limited to, conjugation, electroporation, chemical transformation, transduction, transfection, and ultrasound transformation. For exogenous expression in E. coli or other prokaryotic cells, some nucleic acid sequences in the genes or cDNAs of eukaryotic nucleic acids can encode targeting signals such as an N-terminal mitochondrial or other targeting signal, which can be removed before transformation into prokaryotic host cells, if desired. For example, removal of a mitochondrial leader sequence led to increased expression in E. coli (Hoffmeister et al., J. Biol. Chem. 280:4329-4338 (2005). For exogenous expression in yeast or other eukaryotic cells, genes can be expressed in the cytosol without the addition of leader sequence, or can be targeted to mitochondrion or other organelles, or targeted for secretion, by the addition of a suitable targeting sequence such as a mitochondrial targeting or secretion signal suitable for the host cells. Thus, it is understood that appropriate modifications to a nucleic acid sequence to remove or include a targeting sequence can be incorporated into an exogenous nucleic acid sequence to impart desirable properties. Furthermore, genes can be subjected to codon optimization with techniques well known in the art to achieve optimized expression of the proteins.

An expression vector or vectors can be constructed to include one or more 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid biosynthetic pathway encoding nucleic acids as exemplified herein operably linked to expression control sequences functional in the host organism. Expression vectors applicable for use in the microbial host organisms include, for example, plasmids, phage vectors, viral vectors, episomes and artificial chromosomes, including vectors and selection sequences or markers operable for stable integration into a host chromosome. Additionally, the expression vectors can include one or more selectable marker genes and appropriate expression control sequences. Selectable marker genes also can be included that, for example, provide resistance to antibiotics or toxins, complement auxotrophic deficiencies, or supply critical nutrients not in the culture media. Expression control sequences can include constitutive and inducible promoTransaminase, transcription enhancers, transcription terminators, and the like which are well known in the art. When two or more exogenous encoding nucleic acids are to be co-expressed, both nucleic acids can be inserted, for example, into a single expression vector or in separate expression vectors. For single vector expression, the encoding nucleic acids can be operationally linked to one common expression control sequence or linked to different expression control sequences, such as one inducible promoter and one constitutive promoter. The transformation of exogenous nucleic acid sequences involved in a metabolic or synthetic pathway can be confirmed using methods well known in the art. Such methods include, for example, nucleic acid analysis such as Northern blots or polymerase chain reaction (PCR) amplification of mRNA, or immunoblotting for expression of gene products, or other suitable analytical methods to test the expression of an introduced nucleic acid sequence or its corresponding gene product. It is understood by those skilled in the art that the exogenous nucleic acid is expressed in a sufficient amount to produce the desired product, and it is further understood that expression levels can be optimized to obtain sufficient expression using methods well known in the art and as disclosed herein.

In some embodiments are methods for producing a desired intermediate or product such as adipate, 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid. For example, a method for producing adipate can involve culturing a non-naturally occurring microbial organism having an adipate pathway, the pathway including at least one exogenous nucleic acid encoding an adipate pathway enzyme expressed in a sufficient amount to produce adipate, under conditions and for a sufficient period of time to produce adipate, the adipate pathway including succinyl-CoA: acetyl-CoA acyl transferase, 3-hydroxyacyl-CoA dehydrogenase, 3-hydroxyadipyl-CoA dehydratransaminasee, adipate semialdehydereductransaminasee, and adipyl-CoA synthetransaminasee or phosphotransadipylase/adipate kinase or adipyl-CoA: acetyl-CoA transferase or adipyl-CoA hydrolase. Additionally, a method for producing adipate can involve culturing a non-naturally occurring microbial organism having an adipate pathway, the pathway including at least one exogenous nucleic acid encoding an adipate pathway enzyme expressed in a sufficient amount to produce adipate, under conditions and for a sufficient period of time to produce adipate, the adipate pathway including succinyl-CoA: acetyl-CoA acyl transferase, 3-oxoadipyl-CoA transferase, 3-oxoadipate reductransaminasee, 3-hydroxyadipate dehydratransaminasee, and 2-enoate reductransaminasee.

Further, a method for producing 6-aminocaproic acid can involve culturing a non-naturally occurring microbial organism having a 6-aminocaproic acid pathway, the pathway including at least one exogenous nucleic acid encoding a 6-aminocaproic acid pathway enzyme expressed in a sufficient amount to produce 6-aminocaproic acid, under conditions and for a sufficient period of time to produce 6-aminocaproic acid, the 6-aminocaproic acid pathway including CoA-dependent trans-enoyl-CoA reductransaminasee and transaminase or 6-aminocaproate dehydrogenase. Additionally, a method for producing caprolactam can involve culturing a non-naturally occurring microbial organism having a caprolactam pathway, the pathway including at least one exogenous nucleic acid encoding a caprolactam pathway enzyme expressed in a sufficient amount to produce caprolactam, under conditions and for a sufficient period of time to produce caprolactam, the caprolactam pathway including CoA-dependent aldehyde dehydrogenase, transaminase or 6-aminocaproate dehydrogenase, and amidohydrolase.

Suitable purification and/or assays to test for the production of 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid can be performed using well known methods. Suitable replicates such as triplicate cultures can be grown for each engineered strain to be tested. For example, product and byproduct formation in the engineered production host can be monitored. The final product and intermediates, and other organic compounds, can be analyzed by methods such as HPLC (High Performance Liquid Chromatography), GC-MS (Gas Chromatography-Mass Spectroscopy) and LC-MS (Liquid Chromatography-Mass Spectroscopy) or other suitable analytical methods using routine procedures well known in the art. The release of product in the fermentation broth can also be tested with the culture supernatant. Byproducts and residual glucose can be quantified by HPLC using, for example, a refractive index detector for glucose and alcohols, and a UV detector for organic acids (Lin et al., Biotechnol. Bioeng. 90:775-779 (2005)), or other suitable assay and detection methods well known in the art. The individual enzyme activities from the exogenous DNA sequences can also be assayed using methods well known in the art.

The 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid can be separated from other components in the culture using a variety of methods well known in the art. Such separation methods include, for example, extraction procedures as well as methods that include continuous liquid-liquid extraction, pervaporation, membrane filtration, membrane separation, reverse osmosis, electrodialysis, distillation, crystallization, centrifugation, extractive filtration, ion exchange chromatography, size exclusion chromatography, adsorption chromatography, and ultrafiltration. All of the above methods are well known in the art.

Any of the non-naturally occurring microbial organisms described herein can be cultured to produce and/or secrete the biosynthetic products. For example, the 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid producers can be cultured for the biosynthetic production of 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid.

For the production of 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid, the recombinant strains are cultured in a medium with carbon source and other essential nutrients. It is sometimes desirable and can be highly desirable to maintain anaerobic conditions in the fermenter to reduce the cost of the overall process. Such conditions can be obtained, for example, by first sparging the medium with nitrogen and then sealing the flasks with a septum and crimp-cap. For strains where growth is not observed anaerobically, microaerobic or substantially anaerobic conditions can be applied by perforating the septum with a small hole for limited aeration. Exemplary anaerobic conditions have been described previously and are well-known in the art. Exemplary aerobic and anaerobic conditions are described, for example, in U.S. Pat. No. 7,947,483 issued May 24, 2011. Fermentations can be performed in a batch, fed-batch or continuous manner, as disclosed herein.

If desired, the pH of the medium can be maintained at a desired pH, in particular neutral pH, such as a pH of around 7 by addition of a base, such as NaOH or other bases, or acid, as needed to maintain the culture medium at a desirable pH. The growth rate can be determined by measuring optical density using a spectrophotometer (600 nm), and the glucose uptake rate by monitoring carbon source depletion over time.

The growth medium can include, for example, any carbohydrate source which can supply a source of carbon to the non-naturally occurring microorganism. Such sources include, for example, sugars such as glucose, xylose, arabinose, galactose, mannose, fructose, sucrose and starch. Other sources of carbohydrate include, for example, renewable feedstocks and biomass. Exemplary types of biomasses that can be used as feedstocks in the methods include cellulosic biomass, hemicellulosic biomass and lignin feedstocks or portions of feedstocks. Such biomass feedstocks contain, for example, carbohydrate substrates useful as carbon sources such as glucose, xylose, arabinose, galactose, mannose, fructose and starch. Given the teachings and guidance provided herein, those skilled in the art will understand that renewable feedstocks and biomass other than those exemplified above also can be used for culturing the microbial organisms for the production of 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid.

In addition to renewable feedstocks such as those exemplified above, the 6-aminocaproic acid, caprolactam, hexamethylenediamine, or levulinic acid microbial organisms also can be modified for growth on syngas as its source of carbon. In this specific embodiment, one or more proteins or enzymes are expressed in the 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid producing organisms to provide a metabolic pathway for utilization of syngas or other gaseous carbon source.

Synthesis gas, also known as syngas or producer gas, is the major product of gasification of coal and of carbonaceous materials such as biomass materials, including agricultural crops and residues. Syngas is a mixture primarily of H2 and CO and can be obtained from the gasification of any organic feedstock, including but not limited to coal, coal oil, natural gas, biomass, and waste organic matter. Gasification is generally carried out under a high fuel to oxygen ratio. Although largely H2 and CO, syngas can also include CO2 and other gases in smaller quantities. Thus, synthesis gas provides a cost effective source of gaseous carbon such as CO and additionally, CO2.

The Wood-Ljungdahl pathway catalyzes the conversion of CO and H2 to acetyl-CoA and other products such as acetate. Organisms capable of utilizing CO and syngas also generally have the capability of utilizing CO2 and CO2/H2 mixtures through the same basic set of enzymes and transformations encompassed by the Wood-Ljungdahl pathway. H2-dependent conversion of CO2 to acetate by microorganisms was recognized long before it was revealed that CO also could be used by the same organisms and that the same pathways were involved. Many acetogens have been shown to grow in the presence of CO2 and produce compounds such as acetate as long as hydrogen is present to supply the necessary reducing equivalents (see for example, Drake, Acetogenesis, pp. 3-60 Chapman and Hall, New York, (1994)). This can be summarized by the following equation:

2 CO2+4 H2+n ADP+n Pi→CH3COOH+2 H2O+n ATP

Hence, non-naturally occurring microorganisms possessing the Wood-Ljungdahl pathway can utilize CO2 and H2 mixtures as well for the production of acetyl-CoA and other desired products.

The Wood-Ljungdahl pathway is well known in the art and consists of 12 reactions which can be separated into two branches: (1) methyl branch and (2) carbonyl branch. The methyl branch converts syngas to methyl-tetrahydrofolate (methyl-THF) whereas the carbonyl branch converts methyl-THF to acetyl-CoA. The reactions in the methyl branch are catalyzed in order by the following enzymes: ferredoxin oxidoreductransaminasee, formate dehydrogenase, formyltetrahydrofolate synthetransaminasee, methenyltetrahydrofolate cyclodehydratransaminasee, methylenetetrahydrofolate dehydrogenase and methylenetetrahydrofolate reductransaminasee. The reactions in the carbonyl branch are catalyzed in order by the following enzymes or proteins: cobalamide corrinoid/iron-sulfur protein, methyltransferase, carbon monoxide dehydrogenase, acetyl-CoA synthase, acetyl-CoA synthase disulfide reductransaminasee and hydrogenase, and these enzymes can also be referred to as methyltetrahydrofolate:corrinoid protein methyltransferase (for example, AcsE), corrinoid iron-sulfur protein, nickel-protein assembly protein (for example, AcsF), ferredoxin, acetyl-CoA synthase, carbon monoxide dehydrogenase and nickel-protein assembly protein (for example, CooC). Following the teachings and guidance provided herein for introducing a sufficient number of encoding nucleic acids to generate a 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid pathway, those skilled in the art will understand that the same engineering design also can be performed with respect to introducing at least the nucleic acids encoding the Wood-Ljungdahl enzymes or proteins absent in the host organism. Therefore, introduction of one or more encoding nucleic acids into the microbial organisms such that the modified organism contains the complete Wood-Ljungdahl pathway will confer syngas utilization ability.

Additionally, the reductive (reverse) tricarboxylic acid cycle coupled with carbon monoxide dehydrogenase and/or hydrogenase activities can also be used for the conversion of CO, CO2 and/or H2 to acetyl-CoA and other products such as acetate. Organisms capable of fixing carbon via the reductive TCA pathway can utilize one or more of the following enzymes: ATP citrate-lyase, citrate lyase, aconitransaminasee, isocitrate dehydrogenase, alpha-ketoglutarate: ferredoxin oxidoreductransaminasee, succinyl-CoA synthetransaminasee, succinyl-CoA transferase, fumarate reductransaminasee, fumarase, malate dehydrogenase, NAD(P)Ferredoxin oxidoreductransaminasee, carbon monoxide dehydrogenase, and hydrogenase. Specifically, the reducing equivalents extracted from CO and/or H2 by carbon monoxide dehydrogenase and hydrogenase are utilized to fix CO2 via the reductive TCA cycle into acetyl-CoA or acetate. Acetate can be converted to acetyl-CoA by enzymes such as acetyl-CoA transferase, acetate kinase/phosphotransacetylase, and acetyl-CoA synthetransaminasee. Acetyl-CoA can be converted to the p-toluate, terepathalate, or (2-hydroxy-3-methyl-4-oxobutoxy) phosphonate precursors, glyceraldehyde-3-phosphate, phosphoenolpyruvate, and pyruvate, by pyruvate: ferredoxin oxidoreductransaminasee and the enzymes of gluconeogenesis. Following the teachings and guidance provided herein for introducing a sufficient number of encoding nucleic acids to generate a p-toluate, terephthalate or (2-hydroxy-3-methyl-4-oxobutoxy) phosphonate pathway, those skilled in the art will understand that the same engineering design also can be performed with respect to introducing at least the nucleic acids encoding the reductive TCA pathway enzymes or proteins absent in the host organism. Therefore, introduction of one or more encoding nucleic acids into the microbial organisms such that the modified organism contains the complete reductive TCA pathway will confer syngas utilization ability.

Given the teachings and guidance provided herein, those skilled in the art will understand that a non-naturally occurring microbial organism can be produced that secretes the biosynthesized compounds when grown on a carbon source such as a carbohydrate. Such compounds include, for example, 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid and any of the intermediate metabolites in the 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid pathway. All that is required is to engineer in one or more of the required enzyme activities to achieve biosynthesis of the desired compound or intermediate including, for example, inclusion of some or all of the 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid biosynthetic pathways. Accordingly, some embodiments provide a non-naturally occurring microbial organism that produces and/or secretes 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid when grown on a carbohydrate and produces and/or secretes any of the intermediate metabolites shown in the 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid pathway when grown on a carbohydrate. For example, an adipate producing microbial organisms can initiate synthesis from an intermediate, for example, 3-oxoadipyl-CoA, 3-hydroxyadipyl-CoA, 5-carboxy-2-pentenoyl-CoA, or adipyl-CoA (see FIG. 1), as desired. In addition, an adipate producing microbial organism can initiate synthesis from an intermediate, for example, 3-oxoadipyl-CoA, 3-oxoadipate, 3-hydroxyadipate, or hexa-2-enedioate. The 6-aminocaproic acid producing microbial organism can initiate synthesis from an intermediate, for example, adipate semialdehyde. The caprolactam producing microbial organism can initiate synthesis from an intermediate, for example, adipate semialdehyde or 6-aminocaproic acid (see FIG. 1), as desired.

In some embodiments, the non-naturally occuring microrganisms can generate adipate, 6ACA, caprolactone, hexamethyelenediamine or caproclactam as shown in FIG. 4-9.

In some embodiments, the non-naturally occurring microbial organisms further include an exogenously expressed nucleic acid encoding an aldehyde dehydrognease (ALD) or a transenoyl reductase (TER) or both. The ALD reacts with adipyl-CoA to produce adipate semialdehyde, whereas the TER reacts with 5-carboxy-2-pentenoyl-CoA (CPCoA) to form adipylCoA.

In some embodiments, the ALD enzymes have greater catalytic efficiency and activity for the adipyl CoA substrate as compared to succinyl-CoA, or acetyl-CoA, or both substrates. In some embodiments, the ALD enzymes are as shown in Table 2.

TABLE 2 Activity of Aldehyde Dehydrogenases on Adipyl-CoA Accession Activity- Activity- NO. Organism No/SEQ ID NO. NADH NADPH 1 Clostridium kluyveri SEQ ID NO: 141 − + DSM555 2 Porphyromonas SEQ ID NO: 142 + − gingivalis W83 3 Clostridium difficile 630 SEQ ID NO: 143 − + 4 Kluyvera intestini WP_071196317.1 + − 5 Clostridium neonatale WP_058295546.1 − − 6 Aerococcus sp. WP_070558456.1 − − HMSC062B07 7 Peptostreptococcaceae WP_021676458.1 + − bacterium oral 8 Dasania marina WP_026244399.1 − − 9 Porphyromonadaceae WP_036830068.1 − − bacterium COT-184 10 Clostridium lundense WP_027623222.1 − − 11 Anaerocolumna jejuensis WP_073279774.1 + − 12 Clostridium WP_052222510.1 − − homopropionicum 13 Geosporobacter WP_069981616.1 − − ferrireducens 14 Listeria ivanovii WP_038407128.1 − − 15 Bacillus soli WP_066062455.1 + − 16 Enterococcus rivorum WP_069697141.1 − − 17 Desnuesiella massiliensis WP_055665162.1 + − 18 Bacteroidales bacterium WP_066041885.1 − − KA00251 19 Caldanaerobius WP_026487268.1 + − polysaccharolyticus 20 Clostridium sp. ASF356 WP_004036483.1 − − 21 Clostridiales bacterium WP_034420506.1 − − DRI-13 22 Fusobacterium ulcerans WP_005981617.1 − − ATCC 49185 23 Anaerocolumna jejuensis WP_073279351.1 − − 24 Cellulosilyticum WP_070001026.1 + − sp. I15G10I2 25 Geosporobacter WP_083273866.1 + − ferrireducens 26 Pelosinus sp. UFO1 WP_038668911.1 − − 27 Bacillus korlensis WP_084362095.1 + − 28 Acidaminococcus WP_075579339.1 + − massiliensis 29 Eubacterium sp. SB2 WP_050640767.1 − − 30 Erwinia teleogrylli WP_058911295.1 − − 31 Lachnospiraceae WP_016223553.1 + − bacterium 32 32 Eubacterium WP_004061597.1 + − plexicaudatum 33 Clostridium sp. WP_033166114.1 + − KNHs205 34 Butyricimonas virosa WP_027200274.1 − − 35 Malonomonas rubra WP_072908980.1 − − 36 Robinsoniella peoriensis WP_044292972.1 + − 37 Clostridium WP_069679818.1 − − taeniosporum 38 Caldithrix abyssi WP_006928331.1 + − 39 Piscicoccus intestinalis WP_084343789.1 − − 40 Sporomusa sphaeroides WP_075753933.1 + − 41 Bacillus sp. FJAT-25547 WP_057762439.1 + − 42 Dorea sp. D27 WP_049729435.1 + − 43 Oscillibacter sp. 13 WP_081646270.1 − − 44 Enterococcus WP_010767571.1 + − phoeniculicola 45 Blautia schinkii WP_044941637.1 + − 46 Shuttleworthia satelles WP_006905683.1 − − DSM 14600 47 Clostridium intestinale WP_073018444.1 + − 48 Massilioclostridium coli WP_069989048.1 − − 49 Cloacibacillus porcorum WP_066745012.1 − − 50 Clostridium sp. CL-2 WP_032120205.1 − − 51 Clostridia bacterium WP_054330586.1 − − UC5.1-1D10 52 Methylobacterium sp. WP_082772960.1 − − CCH5-D2 53 Sporosarcina globispora WP_053435653.1 + + 54 Lachnospiraceae WP_031546337.1 − − bacterium AC3007 55 Lachnospiraceae WP_016290199.1 − − bacterium 28-4 56 Enterococcus avium WP_034875865.1 − − 57 Desulfotomaculum WP_027356260.1 − − thermocisternum 58 Rhodobacter aestuarii WP_076486054.1 + − 59 Clostridium grantii WP_073337420.1 + − 60 Collinsella sp. GD7 WP_066830323.1 + − 61 Clostridium WP_07161 1886.1 − − estertheticum 62 bacterium MS4 WP_038325413.1 − − 63 Clostridium WP_009268007.1 + − glycyrrhizinilyticum 64 Bacillus horikoshii WP_082892049.1 − − 65 Thermincola ferriacetica WP_052218568.1 + − 66 Lachnospiraceae WP_035653923.1 + − bacterium AC3007 67 Eubacterium sp. 14-2 WP_016216571.1 + − 68 Candidates WP_069895590.1 − − Marispirochaeta associata 69 Clostridium drakei WP_032078293.1 − − 70 Halanaerobium kushneri WP_076543773.1 − − 71 Clostridium fallax WP_072896506.1 − − 72 Flavonifractor plautii WP_009261118.1 − − 73 Clostridium propionicum WP_066049640.1 − − 74 Anaerosalibacter WP_042682918.1 + − massiliensis 75 Clostridium indolis WP_024295710.1 + − DSM 755 76 Gabonibacter WP_059027034.1 − − massiliensis 77 Catabacter WP_046444791.1 + + hongkongensis 78 Desulfitibacter WP_028307735.1 − − alkalitolerans 79 Porphyromonas levii WP_018357742.1 − − 80 Bacillus thermotolerans WP_039235348.1 + − 81 Desulfitibacter WP_028307055.1 − − alkalitolerans 82 Gracilibacillus kekensis WP_073203236.1 + + 83 Lactonifactor WP_072848455.1 − − longoviformis 84 Propionispora sp. 2/2-37 WP_054258533.1 + − 85 Erysipelothrix larvae WP_067632640.1 − − 86 Clostridium chauvoei WP_021875658.1 + − 87 Thermoanaerobacterium WP_014757178.1 + − aotearoense 88 Ruminococcus sp. AT10 WP_059066688.1 + − 89 Porphyromonas sp. WP_070707924.1 − − HMSC077F02 90 Acetobacterium WP_026396046.1 + − dehalogenans 91 Spirochaeta alkalica WP_018526526.1 + − 92 Alistipes sp. Z0R0009 WP_047449305.1 − − 93 Clostridiisalibacter WP_026895448.1 − − paucivorans 94 Clostridium WP_073149471.1 + + caminithermale DSM 15212 95 Caldanaerobius fijiensis WP_073341480.1 + − 96 Clostridium kluyveri WP_073539833.1 − − 97 Pelosinus fermentans WP_007958399.1 + − 98 Halanaerobium WP_005487288.1 − − saccharolyticum subsp. saccharolyticum DSM 6643 99 Anaeroarcus burkinensis WP_018702299.1 − − DSM 6283 100 Blautia wexlerae WP_026648408.1 + − 101 Paenibacillus sp. WP_019424162.1 + − OSY-SE 102 Brachyspira intermedia WP_014488056.1 − − PWSA 103 Spirochaetes bacterium OHD32879.1 + − GWC2_52_13 104 Thermoanaerobacterales KUK31085.1 − − bacterium 50_218 105 Cohaesibacter WP_090072157.1 − − marisflavi 106 Gracilibacillus WP_089739945.1 − − ureilyticus 107 Romboutsia WP_092724914.1 + − lituseburensis DSM 108 uncultured SCJ29526.1 − − Clostridium sp. 109 Clostridium sp. CDC62685.1 + − CAG:448 110 Clostridium CCQ95129.1 − − ultunense Esp 111 Yersinia bercovieri WP_005274635.1 + − ATCC 43970 112 Proteocatella sphenisci WP_028829945.1 + − 113 Clostridium sp. MSTE9 WP_009063988.1 − − 114 Spirochaeta africana WP_014454236.1 − − 115 Deltaproteobacteria OGQ13386.1 − − bacterium RIFCSPHIGHO2_02 FULL_40_11 116 Clostridiales bacterium KKM11466.1 − − PH28_bin88 117 Pelosinus propionicus WP_090932308.1 + − DSM 118 Propionispora vibrioides WP_091747803.1 − − 119 Natronincola WP_090549432.1 − − ferrireducens 120 uncultured WP_112331601.1 − − Ruminococcus sp. 121 Firmicutes bacterium WP_022229858.1 − − CAG:41 122 Tannerella sp. oral ETK11816.1 − − 123 Clostridium sp. DL-VIII WP_009171375.1 − − 124 Desulfobulbus japonicus WP_028581706.1 − − 125 Veillonella sp. oral WP_009353657.1 − − 126 Bacillus selenitireducens WP_013174003.1 − − 127 Deltaproteobacteria OGP02283.1 − bacterium GWA2_38_16 128 Clostridiaceae KJS20094.1 − − bacterium BRH 129 Clostridium cadaveris WP_035770223.1 − − 130 Vibrio hangzhouensis WP_103880502.1 − − 131 Halanaerobium SDI24694.1 − − congolense 132 uncultured Eubacterium SCH28733.1 − − sp. 133 Oscillibacter sp. CDB26907.1 − − CAG:241 134 Clostridium sp. KLE ERI68946.1 + − 135 Caldalkalibacillus WP_007505383.1 + − thermarum TA2.A1 136 Budvicia aquatica WP_029095874.1 − − 137 Caldalkalibacillus WP_007505383.1 + − thermarum TA2.A1 138 Rhodospirillum rubrum WP_011388669.1 − − ATCC 11170 139 Bacteroidetes bacterium OFX78235.1 − − GWE2_39_28 140 Desulfosporosinus sp. KJS46946.1 − − BICA1 141 Clostridium uliginosum WP_090094411.1 − − 142 Pseudobutyrivibrio WP_090301343.1 − − sp. ACV-2 143 Sporolituus WP_093690468.1 − − thermophilus DSM 144 Eubacteriaceae WP_087275421.1 − − bacterium CHKCI004 145 Blautia sp. CAG:257 CDA04862.1 + − 146 Listeria marthii FSL EFR88049.1 + − 147 Desulfosporosinus WP_009624792.1 − − sp. OT 148 Clostridium WP_024346771.1 + − methoxybenzovorans 149 Bacillus sp. m3-13 WP_010197697.1 + − 150 bacterium OIP28307.1 + − CG2_30_54_10 151 Halanaerobium ODS50009.1 − − sp. 4-GBenrich 152 Candidatus KFZ26741.1 + + Izimaplasma sp. 153 Desulfotomaculum WP_092244224.1 − − guttoideum 154 Bacillus daliensis WP_090843272.1 − − 155 Sporomusa acidovorans WP_093796665.1 − − 156 Clostridium sp. WP_089994985.1 − − C105KSO15 157 Firmicutes bacterium CCZ36420.1 + − CAG:41 158 Fusobacterium WP_085057258.1 + − nucleatum subsp. 159 Thermoanaerobacterium WP_013788835.1 + − xylanolyticum LX-11 160 Enterococcus pallens WP_010758150.1 − − 161 Porphyromonas uenonis WP_007364879.1 − − 162 Tenericutes bacterium OHE32257.1 − − GWD2_38_27 163 Clostridia bacterium KUO67763.1 − − BRH_c25 164 Listeria monocytogenes WP_012951491.1 + − 165 Clostridium lavalense WP_092361844.1 + − 166 Acetanaerobacterium WP_092640331.1 + − elongatum 167 Alkaliphilus WP_091539210.1 + − peptidifermentans DSM 168 Clostridium sp. WP_089983798.1 − − C105KSO15 169 Ruminococcus sp. CCY97458.1 − − CAG:17 170 Clostridium hylemonae EEG72288.1 − − DSM 15053 171 Acetonema longum EGO64744.1 − − DSM 6540 172 Brachyspira innocens WP_020003501.1 − − 173 Clostridium WP_022747467.1 − − saccharobutylicum 174 Tenericutes bacterium OHE28831.1 − − GWD2_38_27 175 Bacillus sp. FJAT-25547 WP_053476394.1 − − 176 Clostridium populeti WP_092561044.1 + − 177 Natronincola WP_090442614.1 − − peptidivorans 178 Megasphaera WP_091 652222.1 − − paucivorans 179 Anaerobium WP_091232027.1 − − acetethylicum 180 Eubacterium limosum ALU13318.1 − − 181 Porphyromonas sp. CCY08492.1 − − CAG:1061 182 Clostridium beijerinckii AAD31841.1 − − strain NRRL B593 183 Clostridium sticklandii WP_013360893.1 − − DSM 519 184 Bacillus oryziterrae WP_017754440.1 − − 185 Yersinia enterocolitica WP_005157703.1 − − 186 Syntrophobacterales OHE18777.1 − − bacterium GWC2_56_13 187 Candidatus Bacteroides KQM08700.1 + − periocalifornicus 188 Anaerocolumna WP_091689178.1 + − aminovalerica 189 Natronincola WP_090439673.1 − − peptidivorans 190 Dendrosporobacter WP_092070189.1 − − quercicolus 191 uncultured SCJ32847.1 − − Flavonifractor sp. 192 Geobacillus sp. OUM85091.1 − − Y4.1MC1 193 Clostridium bolteae CCX97030.1 − − CAG:59 194 Roseburia inulinivorans WP_118109132.1 − − A2-194

In some embodiments, the TER enzymes are as shown in Table 3.

TABLE 3 5-carboxy-2-pentenoyl-CoA reductases Candidate Accession No/ Activity Activity # Species SEQ ID NO. CP-CoA Cr-CoA 1 Candida tropicalis XP_026596596.1/ + + SEQ ID NO: 144 2 Coraliomargarita WP_013043307.1 − ND akajimensis DSM 45221 3 Vibrio WP_009599222.1 − ND caribbenihicus ATCC BAA-2122 4 Cephaloticoccus WP_068629633.1 + ND primus 5 Opitutaceae TSB47 WP_068772922.1 + ND 6 Puniceicoccaceae PDH30576.1 + ND MEDG31 7 Rubritalea marina WP_018969548.1 + ND 8 Rubritalea WP_105041881.1 + ND profundi 9 Rubritalea SHK09753.1 + ND squalenifa 10 Verrucomicrobiae PAW64593.1 − ND bacterium 11 Vibrio hepatarius WP_053410267.1 + ND 12 Vibrio natriegens WP_065302224.1 − ND 13 Vibrio owensii WP_009705827.1 − ND LMG 25430 14 Vibrio sp. EJY3 WP_014231565.1 + ND 15 Arabidopsis CAB75790.1 + ND thaliana 16 Rattus norvegicus NP_058905.1 − ND 17 Coraliomargarita OUU72757.1 + ND sp. 18 Haloferula sp. WP_035604676.1 + ND 19 Opitutaceae KRP37089.1 + ND BACL24 20 Opitutaceae EW11 WP_107744621.1 + ND 21 Puniceicoccaceae PDH31188.1 + ND MED-G30 22 Terrimicrobium WP_075078790.1 + ND sacchariphilum 23 Vibrio owensii WP_038894812.1 + ND ATCC 24 Drosophila NP_0610914.2 + + melanogaster SEQ ID NO: 145 25 Homo sapiens NP_057095.4 + ND 26 Euglena gracilis Truncated version of + + Q5EU90.1

The non-naturally occurring microbial organisms are constructed using methods well known in the art as exemplified herein to exogenously express at least one nucleic acid encoding a 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid pathway enzyme in sufficient amounts to produce 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid. It is understood that the microbial organisms are cultured under conditions sufficient to produce 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid. Following the teachings and guidance provided herein, the non-naturally occurring microbial organisms can achieve biosynthesis of 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid resulting in intracellular concentrations between about 0.1-200 mM or more. Generally, the intracellular concentration of 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid is between about 3-150 mM, particularly between about 5-125 mM and more particularly between about 8-100 mM, including about 10 mM, 20 mM, 50 mM, 80 mM, or more. Intracellular concentrations between and above each of these exemplary ranges also can be achieved from the non-naturally occurring microbial organisms.

In some embodiments, culture conditions include anaerobic or substantially anaerobic growth or maintenance conditions. Exemplary anaerobic conditions have been described previously and are well known in the art. Exemplary anaerobic conditions for fermentation processes are described herein and are described, for example, in U.S. Pat. No. 7,947,483, issued May 24, 2011. Any of these conditions can be employed with the non-naturally occurring microbial organisms as well as other anaerobic conditions well known in the art. Under such anaerobic conditions, the 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid producers can synthesize 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid at intracellular concentrations of 5-10 mM or more as well as all other concentrations exemplified herein. It is understood that, even though the above description refers to intracellular concentrations, 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid producing microbial organisms can produce 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid intracellularly and/or secrete the product into the culture medium.

The culture conditions can include, for example, liquid culture procedures as well as fermentation and other large scale culture procedures. As described herein, particularly useful yields of the biosynthetic products can be obtained under anaerobic or substantially anaerobic culture conditions.

As described herein, one exemplary growth condition for achieving biosynthesis of 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid includes anaerobic culture or fermentation conditions. In certain embodiments, the non-naturally occurring microbial organisms can be sustained, cultured or fermented under anaerobic or substantially anaerobic conditions. Briefly, anaerobic conditions refer to an environment devoid of oxygen. Substantially anaerobic conditions include, for example, a culture, batch fermentation or continuous fermentation such that the dissolved oxygen concentration in the medium remains between 0 and 10% of saturation. Substantially anaerobic conditions also include growing or resting cells in liquid medium or on solid agar inside a sealed chamber maintained with an atmosphere of less than 1% oxygen. The percent of oxygen can be maintained by, for example, sparging the culture with an N2/CO2 mixture or other suitable non-oxygen gas or gases.

The culture conditions described herein can be scaled up and gown continuously for manufacturing of 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid. Exemplary growth procedures include, for example, fed-batch fermentation and batch separation; fed-batch fermentation and continuous separation, or continuous fermentation and continuous separation. All of these processes are well known in the art. Fermentation procedures are particularly useful for the biosynthetic production of commercial quantities of 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid. Generally, and as with non-continuous culture procedures, the continuous and/or near-continuous production of 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid will include culturing a non-naturally occurring 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid producing organism in sufficient nutrients and medium to sustain and/or nearly sustain growth in an exponential phase. Continuous culture under such conditions can include, for example, 1 day, 2, 3, 4, 5, 6 or 7 days or more. Additionally, continuous culture can include 1 week, 2, 3, 4 or 5 or more weeks and up to several months. Alternatively, organisms can be cultured for hours, if suitable for a particular application. It is to be understood that the continuous and/or near-continuous culture conditions also can include all time intervals in between these exemplary periods. It is further understood that the time of culturing the microbial organism is for a sufficient period of time to produce a sufficient amount of product for a desired purpose.

Fermentation procedures are well known in the art. Briefly, fermentation for the biosynthetic production of 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid can be utilized in, for example, fed-batch fermentation and batch separation; fed-batch fermentation and continuous separation, or continuous fermentation and continuous separation. Examples of batch and continuous fermentation procedures are well known in the art.

In addition to the above fermentation procedures using the 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid producers for continuous production of substantial quantities of 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid, the 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid producers also can be, for example, simultaneously subjected to chemical synthesis procedures to convert the product to other compounds or the product can be separated from the fermentation culture and sequentially subjected to chemical conversion to convert the product to other compounds, if desired. As described herein, an intermediate in the adipate pathway utilizing 3-oxoadipate, hexa-2-enedioate, can be converted to adipate, for example, by chemical hydrogenation over a platinum catalyst.

As described herein, exemplary growth conditions for achieving biosynthesis of 6-aminocaproic acid, caprolactam, hexamethylenediamine or levulinic acid includes the addition of an osmoprotectant to the culturing conditions. In certain embodiments, the non-naturally occurring microbial organisms can be sustained, cultured or fermented as described above in the presence of an osmoprotectant. Briefly, an osmoprotectant means a compound that acts as an osmolyte and helps a microbial organism as described herein survive osmotic stress. Osmoprotectants include, but are not limited to, betaines, amino acids, and the sugar trehalose. Non-limiting examples of such are glycine betaine, praline betaine, dimethylthetin, dimethylslfonioproprionate, 3-dimethylsulfonio-2-methylproprionate, pipecolic acid, dimethylsulfonioacetate, choline, L-carnitine and ectoine. In one aspect, the osmoprotectant is glycine betaine. It is understood to one of ordinary skill in the art that the amount and type of osmoprotectant suitable for protecting a microbial organism described herein from osmotic stress will depend on the microbial organism used. For example, Escherichia coli in the presence of varying amounts of 6-aminocaproic acid is suitably grown in the presence of 2 mM glycine betaine. The amount of osmoprotectant in the culturing conditions can be, for example, no more than about 0.1 mM, no more than about 0.5 mM, no more than about 1.0 mM, no more than about 1.5 mM, no more than about 2.0 mM, no more than about 2.5 mM, no more than about 3.0 mM, no more than about 5.0 mM, no more than about 7.0 mM, no more than about 10mM, no more than about 50 mM, no more than about 100 mM or no more than about 500 mM.

Successfully engineering a pathway involves identifying an appropriate set of enzymes with sufficient activity and specificity. This entails identifying an appropriate set of enzymes, cloning their corresponding genes into a production host, optimizing fermentation conditions, and assaying for product formation following fermentation. To engineer a production host for the production of 6-aminocaproic acid or caprolactam, one or more exogenous DNA sequence(s) can be expressed in a host microorganism. In addition, the microorganism can have endogenous gene(s) functionally deleted. These modifications will allow the production of 6-aminocaproate or caprolactam using renewable feedstock.

In some embodiments minimizing or even eliminating the formation of the cyclic imine or caprolactam during the conversion of 6-aminocaproic acid to HMDA entails adding a functional group (for example, acetyl, succinyl) to the amine group of 6-aminocaproic acid to protect it from cyclization. This is analogous to ornithine formation from L-glutamate in Escherichia coli. Specifically, glutamate is first converted to N-acetyl-L-glutamate by N-acetylglutamate synthase. N-Acetyl-L-glutamate is then activated to N-acetylglutamyl-phosphate, which is reduced and transaminated to form N-acetyl-L-ornithine. The acetyl group is then removed from N-acetyl-L-omithine by N-acetyl-L-ornithine deacetylase forming L-ornithine. Such a route is necessary because formation of glutamate-5-phosphate from glutamate followed by reduction to glutamate-5-semialdehyde leads to the formation of (S)-1-pyrroline-5-carboxylate, a cyclic imine formed spontaneously from glutamate-5-semialdehyde. In the case of forming HMDA from 6-aminocaproic acid, the steps can involve acetylating 6-aminocaproic acid to acetyl-6-aminocaproic acid, activating the carboxylic acid group with a CoA or phosphate group, reducing, aminating, and deacetylating.

EXPERIMENTS Example 1 Identification of Transaminases with Activity on 6-Aminocaproic Acid (6ACA)

Genes encoding transaminases were identified bioinformatically from metagenomic libraries and public databases using a basic local alignment search tool (BLAST) (Table 4). Genes encoding each of the transaminases were synthesized, expressed in, and evaluated for catalytic activity on 6-aminocaproic acid (6ACA) and y-aminobutyric acid (GABA) using an enzyme-coupled assay.

The genes encoding the TA enzyme candidates of Table 4 were cloned into a low copy number vector under a constitutive promoter and the constructs were transformed into E. coli using standard techniques. Transformants were cultured in LB medium in the presence of antibiotic overnight at 35° C., after which the cells were spun down at 15,000×g at room temperature. To make lysates, the supernatants were removed and E. coli cells expressing the TA gene were resuspended in a chemical lysis solution containing lysozyme, nuclease, and 10 mM DTT. Lysates were used immediately.

The transaminase assay solution contained 0.1 M Tris-HCl, pH 8.0; 0.3 mM 6ACA, 0.3 mM GABA, or 20 mM Ala; 0.1 mM γ-ketoglutarate; 1 mM NAD; and 50 U/mL glutamate dehydrogenase. The assay was initiated by adding the TA lysate and conducted at room temperature. Activity was monitored by an increase in absorbance of NADH at 340 nm relative to a lysate that contained no TA. The linear rate was calculated as Aabs/min. Rates >100 were designated as (++), rates between 1-100 were designated as (+), and rates with little to no activity were a designated (−). ND =not determined.

Table 4 shows that TA homologs 1, 3, 4, 5, 9, 12, 26, 27, 30, 31, 38, 50, 64, 74, 78, 79, 81, 91, 106, 108, and 116 have the highest activity levels on 6ACA.

TABLE 4 Transaminase Candidate Genes In vivo Homolog Active Active 6ACA # Organism SEQ ID NO: Accession No. 6ACA GABA Production 1 Achromobacter SEQ ID NO: 1  WP_013395096.1 ++ ++ + xylosoxidans 2 Metagenomic HAC67230.1 − ++ 3 Metagenomic SEQ ID NO: 3  WP_100856578.1 ++ ++ + 4 Metagenomic SEQ ID NO: 4  WP_025513437.1 ++ ++ 5 Metagenomic SEQ ID NO: 5  WP_056075635.1 ++ ++ 6 Metagenomic WP_017521342.1 + ++ 7 Metagenomic WP_017201530.1 ND ND 8 Metagenomic WP_059316136.1 + ++ 9 Metagenomic SEQ ID NO: 9  WP_024817707.1 ++ ++ 10 Metagenomic WP_093015681.1 + ++ 11 Metagenomic WP_069902234.1 − ++ 12 Metagenomic SEQ ID NO: 12 WP_009357183.1 ++ ++ 13 Paenarthrobacter SEQ ID NO: 13 SEQ ID NO: 30 + ++ + aurescens TC1 14 Metagenomic WP_052967527.1 − ++ 15 Metagenomic SEQ ID NO: 15 + ++ 16 Metagenomic WP_043819139.1 − + 17 Metagenomic WP_062073360.1 + ++ 18 Metagenomic WP_015937959.1 + ++ 19 Metagenomic WP_078774761.1 + ++ 20 Metagenomic WP_046815379.1 + ++ 21 Metagenomic WP_090288152.1 − + 22 Metagenomic WP_056075635.1 ND ND 23 Metagenomic WP_003220503.1 − − 24 Metagenomic WP_003255866.1 − + 25 Metagenomic WP_104171925.1 − + 26 Metagenomic SEQ ID NO: 26 WP_123429804.1 ++ ++ + 27 Metagenomic SEQ ID NO: 27 WP_030536079.1 ++ ++ + 28 Metagenomic WP_040078233.1 + ++ 29 Metagenomic EQM68262.1 − − 30 Metagenomic SEQ ID NO: 30 WP_026539700.1 ++ ++ 31 Metagenomic SEQ ID NO: 31 WP_012250302.1 ++ ++ + 32 Metagenomic WP_007983072.1 − − 33 Metagenomic WP_045059477.1 − + 34 Metagenomic WP_093432282.1 − ++ 35 Metagenomic WP_125050266.1 − ++ 36 Metagenomic SEQ ID NO: 36 − ++ 37 Metagenomic WP_134929664.1 − − 38 Metagenomic SEQ ID NO: 38 WP_056075635.1 ++ ++ 39 Metagenomic WP_065926318.1 − − 40 Metagenomic WP_123366550.1 − − 41 Metagenomic WP_019473946.1 − ++ 42 Metagenomic WP_065926966.1 − ++ 43 Metagenomic WP_121733815.1 − ++ 44 Metagenomic WP_015937959.1 − − 45 Metagenomic WP_071291640.1 + + 46 Metagenomic WP_111045681.1 − − 47 Metagenomic WP_056737712.1 + ++ 48 Metagenomic WP_042650496.1 − ++ 49 Metagenomic WP_106886181.1 + ++ 50 Metagenomic SEQ ID NO: 50 WP_056563276.1 ++ ++ + 51 Metagenomic WP_017197131.1 + ++ 52 Metagenomic SEQ ID NO: 52 WP_099790225.1 + ++ + 53 Metagenomic WP_048393168.1 − + 54 Metagenomic WP_123366550.1 − ++ 55 Metagenomic WP_017391017.1 + ++ 56 Metagenomic SEQ ID NO: 56 + ++ 57 Metagenomic WP_056075635.1 − − 58 Metagenomic WP_054597933.1 − − 59 Metagenomic WP_095746204.1 − − 60 Metagenomic WP_003220503.1 − − 61 Metagenomic WP_017197131.1 − − 62 Metagenomic WP_052967527.1 − ++ 63 Metagenomic WP_021472307.1 − − 64 Arthrobacter SEQ ID NO: 64 WP_055239729.1 ++ ++ + sp. Edens01 65 Arthrobacter WP_074699490.1 − − crytallopoietes 66 Arthrobacter WP_079941468.1 − ++ sp. KI72 67 Arthrobacter WP_087028133.1 + ++ agilis 68 Metagenomic WP_119966131.1 + ND 69 Metagenomic RIK89039.1 + ND 70 Metagenomic WP_016152939.1 − ND 71 Metagenomic WP_089085686.1 + ND 72 Metagenomic WP_054094475.1 − ND 73 Metagenomic WP_105516444.1 + ++ 74 Metagenomic SEQ ID NO: 74 WP_123787193.1 ++ ++ 75 Metagenomic WP_088966344.1 − ND 76 Metagenomic WP_119775651.1 + ND 77 Metagenomic SEQ ID NO: 77 + ++ 78 Metagenomic SEQ ID NO: 78 WP_011748622.1 ++ ND 79 Metagenomic SEQ ID NO: 79 WP_111824632.1 ++ ++ 80 Metagenomic HAU57754.1 + ND 81 Metagenomic SEQ ID NO: 81 SHM39441.1 ++ ++ 82 Metagenomic WP_043683590.1 + ND 83 Metagenomic SEQ ID NO: 83 − ND 84 Metagenomic WP_121579846.1 + ND 85 Metagenomic WP_101193102.1 + ND 86 Metagenomic WP_012249988.1 + ++ 87 Metagenomic WP_119775651.1 − ND 88 Metagenomic OGB44516.1 + ND 89 Metagenomic WP_102820733.1 + ND 90 Metagenomic SHM39441.1 + ++ 91 Metagenomic SEQ ID NO: 91 SHM39441.1 ++ ++ 92 Metagenomic WP_088966344.1 + ++ 93 Metagenomic RIK89039.1 + ND 94 Metagenomic WP_043683590.1 + ND 95 Metagenomic WP_137155920.1 + ND 96 Metagenomic WP_099059309.1 + ++ 97 Metagenomic WP_101193102.1 ND ND 98 Metagenomic WP_043683590.1 + ND 99 Metagenomic WP_062685190.1 + ++ 100 Metagenomic WP_081768742.1 + ND 101 Metagenomic ODT51733.1 + ND 102 Metagenomic WP_104959793.1 + ND 103 Metagenomic WP_043683590.1 + ND 104 Metagenomic HAU57754.1 + ND 105 Metagenomic WP_009615038.1 − ND 106 Metagenomic  SEQ ID NO: 106 SHM39441.1 ++ ++ 107 Metagenomic WP_056323744.1 + ++ 108 Metagenomic  SEQ ID NO: 108 WP_056323744.1 ++ ++ 109 Metagenomic WP_088966344.1 + ++ 110 Metagenomic SHM39441.1 + ND 111 Metagenomic WP_125 868825.1 + ND 112 Metagenomic  SEQ ID NO: 112 + ND 113 Metagenomic WP_124644434.1 + ND 114 Metagenomic WP_101193102.1 + ND 115 Metagenomic WP_057067610.1 + ND 116 Metagenomic  SEQ ID NO: 116 ODT32214.1 ++ ++ 117 Metagenomic WP_136961719.1 + ND 118 Metagenomic WP_093109347.1 − ND 119 Metagenomic WP_043683590.1 + ND 120 Metagenomic WP_043683590.1 − ND 121 Metagenomic WP_008955628.1 + ND 122 Metagenomic SHM39441.1 + ND 123 Metagenomic WP_003832711.1 + ND 124 Metagenomic WP_116003699.1 + ND 125 Metagenomic WP_120809350.1 − ND 126 Metagenomic WP_026133539.1 + ++ 127 Metagenomic WP_119775651.1 + ND 128 Metagenomic SHM39441.1 + ++ 129 Metagenomic WP_043683590.1 + ND 130 Metagenomic WP_015475018.1 − ND 131 Metagenomic WP_047290758.1 ND ND 132 Metagenomic WP_116810265.1 − ND 133 Saccharomyces  SEQ ID NO: 133 + ++ cerevisiae 134 Clostridium  SEQ ID NO: 134 + ++ viride 135 Gulosibacter  SEQ ID NO: 135 + ++ molinativorax 136 Kocuria  SEQ ID NO: 136 ++ ++ rhizophila 137 Arthrobacter  SEQ ID NO: 137 ++ ++ sp. FB24 138 Pseudomonas  SEQ ID NO: 138 + + sp. AAC 139 Pseudomonas  SEQ ID NO: 139 + + putida KG-4 140 Alcaligenes A.  SEQ ID NO: 140 + + faecalis

Example 2 In Vivo Assays of Transaminase Homologs

To test the activity of transaminase homologs in vivo, genes encoding selected transaminases were transformed into a strain of E. coli that also included introduced genes encoding 1) a 3-oxoadipyl-CoA thiolase (ml), 2) a 3-oxoadipyl-CoA dehydrogenase (Hbd), 3) a 3-oxoadipyl-CoA dehydratratase (“crotonase” or Crt), 4) a 5-carboxy-2-pentenoyl-CoA reductases (Ter); and 5) an aldehyde dehydrogenase (Ald). The Thl, Hbd, Crt, Ter, Ald genes are reported in in US 8,377,680 (e. g., Example 8, which is incorporated by reference in its entirety). These genes are introduced in an E. coli strain included all of the pathway enzymes necessary for producing 6-aminocaproate (6ACA), with the exception of the TA enzyme. The genes use

The vectors for expressing the TA genes were transformed into the Thl/Hbd/Crt/Ter/Ald E. coli strain and transformants were tested for 6ACA production. The engineered E. coli cells were fed 2% glucose in minimal media, and after an 18 hour incubation at 35° C., the cells were harvested, and the supernatants were evaluated by analytical HPLC or standard LC/MS analytical method for 6ACA production. As shown in Table 4, expression of genes encoding the Ta enzymes in E. coli that included Thl, Hbd, Crt, Ter, and Ald genes resulted in 6ACA production by these strains.

Example 3 Transaminase Variants

Amino acid positions were identified for mutations in the Homolog 1 TA of Achromobacter xylosoxidans and encoded by SEQ ID NO:1 by examination of the crystal structure of the protein, and a gene encoding SEQ ID NO:1 was subjected to saturation mutagenesis at selected amino acid positions. The resulting variants were tested for activity in the lysate assay as described in Example 1. Results for the TA SEQ ID NO: 1 are shown in FIG. 2. FIG. 2 shows which postions of SEQ ID NO: 1 are important for activity.

Variants were generated by mutating the gene encoding the TA enzyme (SEQ ID NO:1) at amino acid positions for V114, S136, T148, P153, 1203, 1204, P206, V207, V111, T216, A237, T264, M265 and L386 as well as the codons for G19, C22, D70, R94, D99, T109, E112, A113, F137, G144, 1149, K150, Y154, S178, L186, Q208, L234, T242, A315, K318, R338, G336, L386, V390, A406, S416, and A421. Mutations were made singly and in combination with mutations at other amino acid positions. Mutations at the amino acid positions were made using degenerate primer sequences and PCR, where the altered gene sequence mixtures were transformed into E. coli. Transformants were tested in lysate assays as described in Example 1. Clones that provided lysates showing activity higher than wild type controls in the assays were retested in triplicate lysate assays. Clones that continued to demonstrate higher than wild type activity were then prepped for sequence analysis of the TA genes they contained.

Table 5 and FIG. 3 provide the mutations found in the variant TA gene sequences of the active clones. Variants demonstrating higher than wild type activity, denoted “+” or “++”, included single mutations and combinatorial (multiple) mutations in the TA gene. Table 5 shows that multiple variants demonstrated greater activity than the wild type TA (SEQ ID NO:1), with mutations at amino acid positions positions V114, S136, T148, P153, 1203, 1204, P206, V207, V111, T216, A237, T264, M265, L386, G19, C22, D70, R94, D99, T109, E112, A113, F137, G144, 1149, K150, Y154, S178, L186, Q208, L234, T242, A315, K318, R338, G336, L386, V390, A406, 5416, A421, G17, M21, A50, A76, Y77, Q78, 179, G84, F107, T108, K119, G139, M142, A152, P153, E205, G209, G211, D238, M285, A290, G291, G292, L293, Y297, M353, S387, S388, and G392 (positions identified with respect to SEQ ID NO:1) resulting in multiple variants with higher activity than the wild type TA from which they were derived.

In addition, several of the variants were assayed using 20 mM alanine as the substrate instead of 6ACA or GABA.

TABLE 5 Transaminase Variants In vivo 6ACA Variant Amino acid substitutions Active Active Active Pro- # to SEQ ID NO: 1 6ACA GABA Ala duction 1 A113V + ++ ND 2 E112K − − ND 3 I49V + ++ ND 4 T264S + ++ ND 5 G19R C22S D70N L186V + ++ ND K318M G336S S416Y 6 V111A + ++ ND 7 I203L + ++ ND 8 T148I + ++ ND 9 G19R D70N D99E L186V + ++ ND K318M G336S S416N 10 T109S + ++ ND 11 T148V + ++ ND 12 S136A ++ ++ ND 13 Q208R + ++ ND 14 L386V + ++ ND 15 G144C + ++ ND 16 I49V S136A T148I + ++ ND 17 S136C + ++ ND 18 S136G + ++ ND 19 I204K + ++ ND 20 M265C + ++ ND 21 V207E + ++ ND 22 S136A T148I V207E ++ ++ ND 23 V207T + ++ ND 24 I204Q + ++ ND 25 I204T + ++ ND 26 L386C + ++ ND 27 M265N + ++ ND 28 G19R D70N L186V + ++ ND K318M G336S S416Y 29 A237T + ++ ND 30 A237D + ++ ND 31 A237V + ++ ND 32 A237G + ++ ND 33 A237S ++ ++ ND 34 G243C + ++ ND 35 I49V S136A T148I V207E ++ ++ ND 36 M265A + ++ ND 37 T216V + ++ ND 38 G19R D70N F133L L186V + ++ ND K318M G336S S416Y 39 T216A + ++ ND 40 G19R C22S D70N L186V + ++ ND K318M G336S S416Y 41 T216C + ++ ND 42 T242A + ++ ND 43 T264P + ++ ND 44 F137W Y154N + ++ ND 45 Y154N + ++ ND 46 Y154I + ++ ND 47 G19R D70N L186V + ++ ND K318M G336S S416D 48 Y154L + ++ ND 49 Y154V + ++ ND 50 Y154F + ++ ND 51 Y154T + ++ ND 52 Y154C + + ND 53 Y154M + ++ ND 54 S136A T148I ++ ++ ND 55 F137T Y154K − ND + 56 F137I − ND + 57 G19R D70N K150R + ++ ND L186V L234I K318M G336S V390D S416N 58 T148D + ND + 59 L386A + ND + 60 R94H S178T + ++ ND A315V R338L 61 K226TR338L + ++ ND 62 R338L + ++ ND 63 L386C + ND + 64 G19R D70N + ++ ND L186V K318M G336S A406E S416Y 65 G19R D70N L186V + ++ ND K318M G336S L386P S416Y A421E 66 G19R D70N A76G ++ ++ ND L186V K318M G336S L386P S416Y A421E 67 G19R D70N A76Q L186V ++ ++ ND K318M G336S L386P S416Y A421E 68 G19R D70N G139E L186V + ++ ND K318M G336S L386P S416Y A421E 69 G19R D70N L186V G291S ++ ++ ND K318M G336S L386P S416Y A421E 70 G19R D70N L186V G292C ++ ++ ND K318M G336S L386P S416Y A421E 71 G19R I49Y D70N L186V ++ ++ ND K318M G336S L386P S416Y A421E 72 G19R D70N I79V L186V ++ ++ ND K318M G336S L386P S416Y A421E 73 G19R D70N + ++ ND K119Y L186V K318M G336S L386P S416Y A421E 74 G19R D70N L186V ++ ++ ND K318M G336S L386P L293C S416Y A421E 75 G19R D70N L186V ++ ++ ND K318M G336S L386P L293M S416Y A421E 76 G19R D70N M142S ++ ++ ND L186V K318M G336S L386P S416Y A421E 77 G19R D70N M142C ++ ++ ND L186V K318M G336S L386P S416Y A421E 78 G19R D70N M142Y ++ ++ ND L186V K318M G336S L386P S416Y A421E 79 G19R D70N P153D L186V ++ ++ ND K318M G336S L386P S416Y A421E 80 G19R D70N Q78V L186V ++ ++ ND K318M G336S L386P S416Y A421E 81 G19R D70N Q78A L186V ++ ++ ND K318M G336S L386P S416Y A421E 82 G19R D70N Q78Y L186V ++ ++ ND K318M G336S L386P S416Y A421E 83 G19R D70N Q78N L186V ++ ++ ND K318M G336S L386P S416Y A421E 84 G19R D70N V111S L186V ++ ++ ND K318M G336S L386P S416Y A421E 85 G19R D70N ++ ++ ND V111A L186V K318M G336S L386P S416Y A421E 86 G19R D70N Y154W + ++ ND L186V K318M G336S L386P S416Y A421E 87 G19R D70N Y154F L186V ++ ++ ND K318M G336S L386P S416Y A421E 88 G19R D70N Y77F L186V ++ ++ ND K318M G336S L386P S416Y A421E 89 G19R D70N I79V L186V ++ ++ ND K318M G336S L386P S416Y A421E 90 G19R D70N Q78N L186V ++ ++ + + K318M G336S L386P S416Y A421E 91 G19R D70N Q78N I79V ++ ++ ND L186V K318M G336S L386P S416Y A421E 92 G19R D70N Q78Y L186V ++ ++ ND K318M G336S L386P S416Y A421E 93 G19R D70N Q78Y I79V ++ ++ ND L186V K318M G336S L386P S416Y A421E 94 G19R D70N A76G L186V ++ ++ ND K318M G336S L386P S416Y A421E 95 G19R D70N A76G I79V ++ ++ ND L186V K318M G336S L386P S416Y A421E 96 G19R D70N A76G Q78N ++ ++ ND L186V K318M G336S L386P S416Y A421E 97 G19R D70N A76G Q78N ++ ++ ND I79V L186V K318M G336S L386P S416Y A421E 98 G19R D70N A76G Q78Y ++ ++ ND L186V K318M G336S L386P S416Y A421E 99 G19R D70N A76G Q78Y ++ ++ ND I79V L186V K318M G336S L386P S416Y A421E 100 G19R D70N A76G L186V ++ ++ ND K318M G336S L386P S416Y A421E 101 G19R D70N A76Q I79V ++ ++ ND L186V K318M G336S L386P S416Y A421E 102 G19R D70N A76Q Q78N ++ ++ ND L186V K318M G336S L386P S416Y A421E 103 G19R D70N A76Q Q78N ++ ++ + + I79V L186V K318M G336S L386P S416Y A421E 104 G19R D70N A76Q Q78Y − ++ ND L186V K318M G336S L386P S416Y A421E 105 G19R D70N A76Q Q78Y + ++ ND I79V L186V K318M G336S L386P S416Y A421E 106 G19R D70N ++ ++ ND V111A L186V K318M G336S L386P S416Y A421E 107 G19R D70N I79V V111A ++ ++ ND L186V K318M G336S L386P S416Y A421E 108 G19R D70N Q78N V111A ++ ++ ND L186V K318M G336S L386P S416Y A421E 109 G19R D70N Q78N I79V ++ ++ ND V111A L186V K318M G336S L386P S416Y A421E 110 G19R D70N Q78Y V111A ++ ++ + + L186V K318M G336S L386P S416Y A421E 111 G19R D70N Q78Y I79V ++ ++ ND V11A L186V K318M G336S L386P S416Y A421E 112 G19R D70N ++ ++ ND A76G V111A L186V K318M G336S L386P S416Y A421E 113 G19R D70N A76G I79V ++ ++ ND V111A L186V K318M G336S L386P S416Y A421E 114 G19R D70N A76G Q78N ++ ++ ND V111A L186V K318M G336S L386P S416Y A421E 115 G19R D70N A76G Q78N ++ ++ ND I79V V111A L186V K318M G336S L386P S416Y A421E 116 G19R D70N A76G Q78Y ++ ++ ND V111A L186V K318M G336S L386P S416Y A421E 117 G19R D70N A76G ++ ++ ND Q78Y I79V V11A L186V K318M G336S L386P S416Y A421E 118 G19R D70N A76Q V111A ++ ++ ND L186V K318M G336S L386P S416Y A421E 119 G19R D70N A76Q I79V ++ ++ + + V111A L186V K318M G336S L386P S416Y A421E 120 G19R D70N A76Q Q78N ++ ++ ND V111A L186V K318M G336S L386P S416Y A421E 121 G19R D70N A76Q Q78N ++ ++ ND I79V V111A L186V K318M G336S L386P S416Y A421E 122 G19R D70N A76Q Q78Y + ++ ND V111A L186V K318M G336S L386P S416Y A421E 123 G19R D70N A76Q Q78Y + ++ ND I79V V11A L186V K318M G336S L386P S416Y A421E 124 A76Q Q78N I79V L386P + + + + 125 G19R D70N A76Q Q78N ++ ++ ND I79V S136A M142I L186I A290L K318M G336S L386P V390A S416Y A421E 126 G19R D70N A76Q Q78N ++ ++ ND + I79V K318M G336S L386P V390L S416Y A421E 127 G19R D70N A76Q Q78N ++ ++ ND I79V K318M G336S L386P V390L S416Y A421E 128 G19R D70N A76Q Q78N ++ ++ ND I79V S136A L186V Y297F K318M G336S L386V V390A S416Y A421E 129 G19R D70N A76Q Q78N ++ ++ ND I79V S136A A152V L186M A290L Y297F K318M G336S L386I S416Y A421E 130 G19R D70N A76Q ++ ++ + + Q78N I79V A152T L186I Y297F K318M G336S L386V V390L S416Y A421E G19R D70N A76Q Q78N I79V A152T L186I Y297F K318M G336S L386P V390L S416Y A421E 131 G19R D70N A76Q Q78N ++ ++ ND I79V S136G A152T L186M K318M G336S L386V S416Y A421E 132 G19R D70N A76Q Q78N ++ ++ ND I79V A152T L186M A290L K318M G336S L386V S416Y A421E 133 G19R D70N A76Q Q78N ++ ++ ND I79V S136A A152V L186M Y297F K318M G336S L386P V390A S416Y A421E 134 G19R D70N A76Q Q78N ++ ++ ND I79V S136G A152V L186I Y297F K318M G336S L386P S416Y A421E 135 G19R D70N A76Q Q78N ++ ++ ND I79V S136G A152T L186M A290L K318M G336S L386V S416Y A421E 136 G19R D70N A76Q Q78N ++ ++ + + I79V S136A A152V Y297F K318M G336S L386V V390A S416Y A421E 137 G19R D70N A76Q Q78N ++ ++ ND I79V S136A L186M A290L K318M G336S L386I V390L S416Y A421E 138 G19R D70N A76Q Q78N ++ ++ ND I79V S136A A152T L186M K318M G336S L386V S416Y A421E 139 G19R D70N A76Q Q78N ++ ++ ND I79V S136A L186M A290L K318M G336S L386V S416Y A421E 140 G19R D70N A76Q Q78N ++ ++ ND I79V S136A A152T L186I A290L K318M G336S L386V V390L S416Y A421E 141 G19R D70N A76Q Q78N ++ ++ ND I79V S136A L186I K318M G336S L386V Y297F V390A S416Y A421E 142 G19R D70N A76Q Q78N ++ ++ ND I79V S136A K318M G336S L386V V390L S416Y A421E 143 G19R D70N A76Q Q78N ++ ++ ND I79V S136A K318M G336S L386V V390A S416Y A421E 144 G19R D70N A76Q ++ ++ ND Q78N I79V S136G K318M G336S Y297F L386P S416Y A421E 145 G19R D70N A76Q ++ ++ ND Q78N I79V A152T A290L K318M G336S Y297F L386P S416Y A421E 146 G19R D70N A76Q ++ ++ ND Q78N I79V A152T A290L K318M G336S Y297F L386P S416Y A421E 147 G19R D70N A76Q ++ ++ ND Q78N I79V S136A A152T L186A A290L K318M G336S Y297F L386P V390A S416Y A421E 148 G19R D70N A76Q Q78N ++ ++ ND 179V S136G A152V L186M A290L K318M G336S Y297F L386P S416Y A421E 149 G19R D70N A76Q Q78N ++ ++ + + I79V K318M G336S Y297F L386V S416Y A421E 150 G17A G19R D70N + + ND A76Q Q78N I79V L186V K318M G336S L386P S416Y A421E 151 G19K D70N A76Q + + ND Q78N I79V L186V K318M G336S L386P S416Y A421E 152 G19Q D70N A76Q + + ND Q78N I79V L186V K318M G336S L386P S416Y A421E 153 M21Q G19R D70N + + ND A76Q Q78N I79V L186V K318M G336S L386P S416Y A421E 154 M21Q M285I G19R + + ND D70N A76Q Q78N I79V L186V K318M G336S L386P S416Y A421E 155 G17S G19R D70N A76Q + + ND Q78N I79V L186V K318M G336S L386P S416Y A421E 156 G17Y G19R D70N − + ND A76Q Q78N I79V L186V K318M G336S L386P S416Y A421E 157 C22M G19R D70N − + ND A76Q Q78N I79V L186V K318M G336S L386P S416Y A421E 158 C22Y G19R D70N + + ND A76Q Q78N I79V L186V K318M G336S L386P S416Y A421E 159 N70A G19R D70N + + ND A76Q Q78N I79V L186V K318M G336S L386P S416Y A421E 160 N70Y G19R D70N − + ND A76Q Q78N I79V L186V K318M G336S L386P S416Y A421E 161 G19R A76Q Q78N I79V + + ND L186V K318M G336S L386P S416Y A421E 162 G19R D70C A76Q Q78N + + ND I79V L186V K318M G336S L386P S416Y A421E 163 A50N G19R D70N − + ND A76Q Q78N I79V L186V K318M G336S L386P S416Y A421E 164 F107M G19R D70N + + ND A76Q Q78N I79V L186V K318M G336S L386P S416Y A421E 165 F107S G19R D70N − + ND A76Q Q78N I79V L186V K318M G336S L386P S416Y A421E 166 F107Q G19R D70N + + ND A76Q Q78N I79V L186V K318M G336S L386P S416Y A421E 167 T108Q G19R D70N − − ND A76Q Q78N I79V L186V K318M G336S L386P S416Y A421E 168 T108A G19R D70N − + ND A76Q Q78N I79V L186V K318M G336S L386P S416Y A421E 169 E112M G19R D70N − + ND A76Q Q78N I79V L186V K318M G336S L386P S416Y A421E 170 S136D G19R D70N + + ND A76Q Q78N I79V L186V K318M G336S L386P S416Y A421E 171 S136G G19R D70N ++ ++ ND A76Q Q78N I79V L186V K318M G336S L386P S416Y A421E 172 S136A G19R D70N + ++ ND A76Q Q78N I79V L186V K318M G336S L386P S416Y A421E 173 A152M G19R D70N + ++ ND A76Q Q78N I79V L186V K318M G336S L386P S416Y A421E 174 A152V G19R D70N + ++ ND A76Q Q78N I79V L186V K318M G336S L386P S416Y A421E 175 A152C G19R D70N + ++ ND A76Q Q78N I79V L186V K318M G336S L386P S416Y A421E 176 A152L G19R D70N + ++ ND A76Q Q78N I79V L186V K318M G336S L386P S416Y A421E 177 A152T G19R D70N + ++ ND A76Q Q78N I79V L186V K318M G336S L386P S416Y A421E 178 A152Q G19R D70N + ++ ND A76Q Q78N I79V L186V K318M G336S L386P S416Y A421E 179 K150H G19R D70N + + ND A76Q Q78N I79V L186V K318M G336S L386P S416Y A421E 180 G19R D70N A76Q + ++ ND Q78N I79V L186I K318M G336S L386P S416Y A421E 181 G19R D70N A76Q + ++ ND Q78N I79V L186M K318M G336S L386P S416Y A421E 182 E205D G19R D70N + + ND A76Q Q78N I79V L186V K318M G336S L386P S416Y A421E 183 D238E G19R D70N + + ND A76Q Q78N I79V L186V K318M G336S L386P S416Y A421E 184 D238I G19R D70N − + ND A76Q Q78N I79V L186V K318M G336S L386P S416Y A421E 185 G84V G19R D70N + + ND A76Q Q78N I79V L186V K318M G336S L386P S416Y A421E 186 D238M G19R D70N − + ND A76Q Q78N I79V L186V K318M G336S L386P S416Y A421E 187 G209G G19R D70N + ++ ND A76Q Q78N I79V L186V K318M G336S L386P S416Y A421E 188 G211N G19R D70N − + ND A76Q Q78N I79V L186V K318M G336S L386P S416Y A421E 189 T242F G19R D70N − + ND A76Q Q78N I79V L186V K318M G336S L386P S416Y A421E 190 A290D G19R D70N + + ND A76Q Q78N I79V L186V K318M G336S L386P S416Y A421E 191 A290K G19R D70N + + ND A76Q Q78N I79V L186V K318M G336S L386P S416Y A421E 192 A290I G19R D70N + + ND A76Q Q78N I79V L186V K318M G336S L386P S416Y A421E 193 Y297F G19R D70N A76Q + ++ ND Q78N I79V L186V K318M G336S L386P S416Y A421E 194 Y297P G19R D70N + + ND A76Q Q78N I79V L186V K318M G336S L386P S416Y A421E 195 M353N G19R D70N + + ND A76Q Q78N I79V L186V K318M G336S L386P S416Y A421E 196 G19R D70N A76Q + ++ ND Q78N I79V L186V K318F G336S L386P S416Y A421E 197 S387Y G19R D70N + + ND A76Q Q78N I79V L186V K318M G336S L386P S416Y A421E 198 C388A G19R D70N + + ND A76Q Q78N I79V L186V K318M G336S L386P S416Y A421E 199 G389G G19R D70N + + ND A76Q Q78N I79V L186V K318M G336S L386P S416Y A421E 200 G392T G19R D70N − + ND A76Q Q78N I79V L186V K318M G336S L386P S416Y A421E 201 G392N G19R D70N + + ND A76Q Q78N I79V L186V K318M G336S L386P S416Y A421E 202 V390L G19R D70N + ++ ND A76Q Q78N I79V L186V K318M G336S L386P S416Y A421E 203 V390D G19R D70N + + ND A76Q Q78N I79V L186V K318M G336S L386P S416Y A421E 204 V390A G19R D70N + + ND A76Q Q78N I79V L186V K318M G336S L386P S416Y A421E 205 G19R D70N A76Q Q78N + + ND I79V L186V K318M G336S L386P S416W A421E 206 G19R D70N A76Q Q78N + + ND I79V L186V K318M G336S L386P S416C A421E 207 G392A G19R D70N + + ND A76Q Q78N I79V L186V K318M G336S L386P S416Y A421E 208 G19R D70N A76Q Q78N + + ND I79V L186V K318M G336S L386S S416Y A421E 209 G19R D70N A76Q Q78N + + ND I79V L186V K318M G336S L386P S416Y A421D 210 G19R D70N A76Q Q78N ++ ++ ND I79V L186V K318M G336S S416Y A421E 211 G19R D70N A76Q Q78N ++ ++ ND I79V L186V K318M G336S L386V S416Y A421E 212 S136A A152V V386I ++ ++ ND V390A G19R D70N A76Q Q78N I79V K318M G336S Y297F L386V S416Y A421E 213 S136A A152T V390L ++ ++ ND G19R D70N A76Q Q78N I79V K318M G336S Y297F L386I S416Y A421E 214 S136A A152V V186I ++ ++ ND A290L Y297F G19R D70N A76Q Q78N I79V K318M G336S Y297F L386V S416Y A421E 215 S136A V186M Y297F ++ ++ ND G19R D70N A76Q Q78N I79V K318M G336S L386V S416Y A421E 216 S136A A152V G19R ++ ++ ND D70N A76Q Q78N I79V K318M G336S Y297F L386I S416Y A421E 217 G19R D70N A76Q Q78N ++ ++ ND I79V K318M G336S Y297F L386I S416Y A421E 218 V186I V390A ++ ++ ND G19R D70N A76Q Q78N I79V K318M G336S Y297F L386I S416Y A421E 219 S136A G19R ++ ++ ND D70N A76Q Q78N179V K318M G336S Y297F L386V S416Y A421E 220 S136G A152V V186I ++ ++ ND G19R D70N A76Q Q78N I79V K318M G336S Y297F L386V S416Y A421E 221 V186I G19R D70N A76Q ++ ++ ND Q78N I79V K318M G336S Y297F L386V S416Y A421E 222 S136A A290L V390L ++ ++ ND G19R D70N A76Q Q78N I79V K318M G336S Y297F L386V S416Y A421E 223 S136A V186A G19R ++ ++ ND D70N A76Q Q78N I79V K318M G336S Y297F L386V S416Y A421E 224 S136A V186M G19R ++ ++ ND D70N A76Q Q78N I79V K318M G336S Y297F L386V S416Y A421E 225 S136A V186M A290L ++ ++ ND G19R D70N A76Q Q78N I79V K318M G336S Y297F L386V S416Y A421E 226 S136G V186I G19R D70N ++ ++ ND A76Q Q78N I79V K318M G336S Y297F L386V S416Y A421E 227 S136A A152V A290L ++ ++ ND G19R D70N A76Q Q78N I79V K318M G336S Y297F L386V S416Y A421E 228 S136G V186I G19R ++ ++ ND D70N A76Q Q78N I79V K318M G336S Y297F L386V S416Y A421E 229 S136G V186M G19R ++ ++ ND D70N A76Q Q78N I79V K318M G336S Y297F L386V S416Y A421E 230 S136A V186A G19R ++ ++ ND D70N A76Q Q78N I79V K318M G336S Y297F L386V S416Y A421E 231 S136G V186M G19R ++ ++ ND D70N A76Q Q78N I79V K318M G336S Y297F L386V S416Y A421E 232 S136A A152V G19R ++ ++ ND D70N A76Q Q78N I79V K318M G336S Y297F L386V S416Y A421E 233 S136A G19R D70N A76Q ++ ++ ND Q78N I79V K318M G336S Y297F L386V S416Y A421E 

1-51. (canceled)
 52. An engineered transaminase (TA) enzyme comprising at least one alteration of an amino acid of SEQ ID NO:1 or 13 or
 31. 53. The engineered TA of claim 52, wherein the engineered transaminase enzyme is capable of a) forming 6-aminocaproic acid from an adipate semialdehyde substrate; b) forming 6-aminocaproic acid from an adipate semialdehyde substrate at a greater rate as compared to the wild type transaminase; c) having a higher affinity for an adipate semialdehyde substrate as compared to the wild type transaminase; or d) any combination of a), b), and c).
 54. The engineered TA of claim 52, wherein the engineered transaminase comprises one or more amino acid alterations at one or more positions selected from residues V114, S136, T148, P153, 1203, 1204, P206, V207, V111, T216, A237, T264, M265, L386, G19, C22, D70, R94, D99, T109, E112, A113, F137, G144, 1149, K150, Y154, S178, L186, Q208, L234, T242, A315, K318, R338, G336, L386, V390, A406, S416, A421, G17, M21, A50, A76, Y77, Q78, 179, G84, F107, T108, K119, G139, M142, A152, P153, E205, G209, G211, D238, M285, A290, G291, G292, L293, Y297, M353, S387, S388, and G392 or a combination thereof of SEQ ID NO:1.
 55. The engineered TA of claim 52, wherein the at least one amino acid alteration of the engineered protein is an alteration selected from Table 5 and combinations thereof of SEQ ID NO:1.
 56. The engineered TA of claim 52, wherein the amino acid alteration comprises at least two, three, four, five, six, seven, eight, or more of an amino acid of SEQ ID NO:1, 13, or
 31. 57. The engineered TA of claim 52, wherein the engineered TA comprises activity that is at least 20% higher than the activity of the transaminase of SEQ ID NO:1, 13, or 31 with no amino acid alterations.
 58. The engineered TA of claim 52, further comprising expression of the engineered TA in a cell that comprises genes encoding a 3-oxoadipyl-CoA thiolase, a 3-oxoadipyl-CoA dehydrogenase, and a 3-oxoadipyl-CoA dehydratase is able to produce at least 10% more 6ACA than a control cell that expresses the wild type TA from which the engineered TA is derived.
 59. An engineered cell comprising the engineered transaminase of claim
 52. 60. The engineered TA of claim 59, further comprising expression of the engineered TA in a cell that comprises genes encoding a 3-oxoadipyl-CoA thiolase, a 3-oxoadipyl-CoA dehydrogenase, and a 3-oxoadipyl-CoA dehydratase is able to produce at least 10% more 6ACA than a control cell that expresses the wild type TA from which the engineered TA is derived
 61. A non-naturally occurring microbial organism comprising at least one exogenous enzyme, the at least one exogenous enzyme comprising a transaminase enzyme converting adipate semialdehyde to 6-amino caproic acid, the transaminase selected from: (i) a transaminase comprising an amino acid sequence having at least 50% sequence identity to at least 25 or more contiguous amino acids of any of SEQ ID NO: 1, 3, 4, 5, 9, 12, 13, 26, 27, 30, 31, 38, 50, 52, 64, 74, 78, 79, 81, 91, 106, 108, and 116; or (ii) an engineered TA of SEQ ID NO: 1, 13 or
 31. 62. The non-naturally occurring microbial organism of claim 61, wherein the microbial organism further comprises a 6-aminocaproic acid pathway, 6-hydroxy caproic acid pathway, a hexamethylene diamine pathway, caprolactone pathway, or a caprolactam pathway.
 63. The non-naturally occurring microbial organism of claim 61, wherein the non-naturally occurring microbial organism comprises a species of Acinetobacter, Actinobacillus, Anaerobiospirillum, Aspergillus, Bacillus, Clostridium, Corynebacterium, Escherichia, Gluconobacter, Klebsiella, Kluyveromyces, Lactococcus, Lactobacillus, Mannheimia, Pichia, Pseudomonas, Rhizobium, Rhizopus, Saccharomyces, Schizosaccharomyces, Streptomyces, and Zymomonas.
 64. The non-naturally occurring microbial organism of claim 61, wherein the TA is derived from Arthrobacter, Paenarthrobacter, Saccharomyces, Clostridium, Gulosibacter, Kocuria, Pseudomonas, and Alcaligenes.
 65. A non-naturally occurring microbial organism or host cell of claim 61, wherein the non-naturally occurring microbial organism or host cell produces more of one or more of adipate, caproic acid, hexamethylene diamine, caprolactone, or caprolactam than is produced by a control microbial organism or host cell substantially identical to the non-naturally occurring microbial organism or host cell with the exception that the control microbial organism or host cell does not comprise an exogenous transaminase or an exogenous nucleic acid sequence encoding the transaminase.
 66. A method of producing 6-amino caproic acid comprising: culturing a non-naturally occurring microbial organism or host cell organism comprising at least one exogenous enzyme, the at least one exogenous enzyme comprising a transaminase enzyme converting adipate semialdehyde to 6-amino caproic acid, the transaminase selected from: (i) a transaminase comprising an amino acid sequence having at least 50% sequence identity to at least 25 or more contiguous amino acids of any of SEQ ID NO: 1, 3, 4, 5, 9, 12, 13, 26, 27, 30, 31, 38, 50, 52, 64, 74, 78, 79, 81, 91, 106, 108, and 116; or (ii) an engineered TA of SEQ ID NO: 1, 13 or 31; and producing 6-amino caproic acid.
 67. The method of claim 66, further comprising recovering 6-amino caproic acid from the non-naturally occurring microbial organism, the fermentation broth, or both.
 68. The method of claim 66, wherein the microbial organism comprises a 6-aminocaproic acid pathway, 6-hydroxy caproic acid pathway, a hexamethylene diamine pathway, caprolactone pathway, or a caprolactam pathway.
 69. The method of claim 66, wherein the non-naturally occurring microbial organism comprises a species of Acinetobacter, Actinobacillus, Anaerobiospirillum, Aspergillus, Bacillus, Clostridium, Corynebacterium, Escherichia, Gluconobacter, Klebsiella, Kluyveromyces, Lactococcus, Lactobacillus, Mannheimia, Pichia, Pseudomonas, Rhizobium, Rhizopus, Saccharomyces, Schizosaccharomyces, Streptomyces, and Zymomonas.
 70. The method of claim 66, wherein the TA is derived from Arthrobacter, Paenarthrobacter, Saccharomyces, Clostridium, Gulosibacter, Kocuria, Pseudomonas, and Alcaligenes.
 71. The method of claim 66, wherein the non-naturally occurring microbial organism or host cell produces more of one or more of adipate, caproic acid, hexamethylene diamine, caprolactone, or caprolactam than is produced by a control microbial organism or host cell substantially identical to the non-naturally occurring microbial organism or host cell with the exception that the control microbial organism or host cell does not comprise an exogenous transaminase or an exogenous nucleic acid sequence encoding the transaminase. 